Interesting statement considering those Carbs have just like Webers, Dellorto's and Solexes Main jets, Idle Jets, Air Correctors, Needle Jets (Emulsion Tubes) and the Air Corrector's are High speed and low speed (Weber low speed air correction is built into the idle jet with differing F numbers designating the air correction hole size).

In fact they have as many Jets as the others and add a couple more options such as Needle tapers and lengths, Multiple tapers and as well Slide cutaways to add into the mix when tuning.

CV Vacuum Carbs also add into the mix different spring lengths and rates to boot, So they are not actually any simpler.

The Biggest difference is that besides picking a size with Webers etc such as 40mm, 45mm or the rarer 42mm, 48, or 50mm and 55mm base sizes you then can alter Main and Auxiliary Chokes or venturi's to fine tune to the engine characteristics.

With Bike carbs whilst good you must make sure you get the right size to suit from the beginning as there is no way of changing Choke sizes other than a new set of different carbies.

So in truth there are pro's and con's to both approaches and if you know what you are doing both types can be jetted to work, If you do not know then both can and will be problematical to make work right.

Therefore just because you lucked out with a set of bike carbs that worked OK with your particular setup does not mean everyone else will be as lucky unless they do some serious research before jumping in and that applies to all carbs, Car specific or Bike specific.

There are also many different non interchangeable Mikuni and Keihin jets to be aware of with different variations of carbs.

With the FCR Bike carbs there is also a very real problem that can cost you an engine they run what is called a Vacuum plate on the slide and the stock ones have a releif on both sides and they break off a couple of sections of these plates after a while, There are billet replacements relieved on one side only that are better but the vaacuum plate is a weakness in the design to be aware of and check on a regular basis.

Not so bad on a race car but a pain in the Posterior for a road driven vehicle to check for cracks on a regular basis, I see them break more often on single cylinders with stronger vacuum pulses but they do also break on four cylinder engines.

Simple answer really, Factories do not spend money unless they need to therefore get the rubbers as fitted by the factory they did not spend that money and cut into profits for nothing.

Willwood now make a dust sealed caliper, But as with all brakes the only stuff that is legal is engineered or stock.

Yes you heard it right the BRE stands for Brock Racing Enterprises and on both sides of the Pacific they were top of their game. and Both Peter Brocks.

Anodizing is for Aluminium and not all Alloys anodize, However I have noted that for other metals Duplicolor has new Paint that supposedly relicates the look have not tried it yet to say if it is any good.

https://www.duplicolor.com/products/metalCast/

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Matt you certainly make some nice gear, I would add that the Subaru market is also quite buoyant and worth a look after of course you make everything and anything possible for Datto's.

Not hard or expensive to put together check out this site for Home Anodizing.
http://www.bryanpryor.com/anodizing/

I have found that when replacing tail shaft bushes in lots of Datsun's the rear bush out of an auto box is the go as often when searching the manual bush is NLA.
Auto Boxes are much easier to get the bushes for.

These guys do Ignition barrels Blinker stalks Lighting switches wheel studs including long ones like the Nissan Motorsport style etc they are in Marickville but have an Online store for out of area sales check their catalog online heaps more stuff we use.
https://niceproducts.com.au/

0.05 is 2 thou,You are talking about 0.02 difference between both of them so that is less than one thou, Guess what after 5,000 km there could easily be that much variance between any new components as they bed in, such a small amount will not be an issue, We are not talking 22,000 RPM Formulae One here where even the five axis machining centres operate as Electric discharge machining so as not to cause stress in machined components from cutting bits.

Mechanic since the seventies and as well an Engine machinist so there will be no issues as long as you buy the collets that match the valves and retainers to suit the same.