yeah I also have a preignition every now and then, not too sure why this happens.
did you count the turns out from fully seated on your idle mixture screws? mine are out by 1 and one third of a turn and my idle speed screw is 3/4 of a turn in from first contact with the arm

Oh yeah man I know what you mean about being jerky at low rpm!. It is due to the fact that the 38 DGAS carb is a synchronous opening carb and because of that it is less behaved and a bit too responsive to tiny throttle inputs, the 32/36 is a progressive opening carb which means the primary circuit opens first so low rpm opperation is more smooth and controllable but the 38 dgas is more suited to modified engines and flows more.
The vacuum advance seems to work normally but take your time to set up the lean best idle so the idle screw isn't wound too far in causing vacuum to reach the vacuum advance port, by having it only just wound in about half a turn from initial contact vacuum won't reach the advance port and it will idle alot lower.
When I first set up my 38 dgas I had the idle screw turned in about one and a half turns and I had set base timing to 5 degrees with vacuum advance line disconected and pluged and when I reconnected the advance line the timing instantly went to 10 degrees and idle increased by 300rpm so by traking your time to tune it you will enjoy it alot more and understand how it all works

sweet is that like one of those lok-rite lokas that are sold for 4X4's? like a cam ratchet set up or dog clutch mechanism thing?

to check the cam profile I would remove the rocker cover and rocker assembly, get a hold of two dial gauges and set them up on the intake and exhaust pushrods for number 1 cylinder, then set number one piston to top dead centre now just check to see if there is any overlap on the valves and record the points when the push rods begin to move up by using a degree wheel on the end of the crank or looking at the timing cover marks for a roughish reading, also check the height at which the pushrod reaches maximum lift and record it. I don't know what the specs of a stock camshaft are unfortunately, but with the data you get from those readings you could compare it to a chart of cams from different manufacturers and check if it looks similar to any of them

http://www.swmotorsport.com.au/
he sells 38mm Exhaust valves for L series engines, I don't know if that would be any help though, those valves you have are pretty special by the sounds of the radical sizes

cool glad to hear the conversion went nice and smooth Did you use a 60a 5 speed? did you use the same tail shaft?

yep I got 9 too I think I only knew 3 answers there

I paid $270 for my pertronix kit 6 months ago and sold it for $105 to a lucky forum member last week
I bought mine from Auto Pro

I have one on my A15 and it works great, I am using F6 emulsions, 185 air correctors, 50 idle jets and the main jets are 145 but I am using a 2 litre accelerator pump jet and powervalve as the ones I need seem to be hard to find.
I put a photo up on the gallery of the linkage I made up for the stock throttle wheel and cable, if you decide to use the 38 DGAS Weber the pic should help you get it hooked up to the accelerator cable.
Heres a good site for tunuing the Weber 38 DGAS
http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm

I have an A15 with a ported head, competition valve springs, linished valves custom cam 240 degree, .475 lift, .085 intake overlap at TDC, bluebird electronic dizzy, 4-1 extractors and 2 1/2 inch exhaust, Weber 38/38 DGAS carb with choke removed for more flow and a Boshe HEC 715 coil
I am not sure of power output yet but I estimate about 90rwhp