Any details on those round ports? They look like false floors with Devcon or so to fill the former open space below.

I think compliance plates were introduced in 1970 or 1971. So probable your cars were built before then. Are there two vacant holes about 100mm apart on the bulkhead or inner guards for 3mm rivets? That could be a clue as to whether or not there were compliance plates.

That photo is not of the aussie compliance plate but the manufacturer plate. This is what our plates are like https://www.privatefleet.com.au/glossa ... at-is-a-compliance-plate/

Where'd you get the flares? Looks good.

As for marks...

A gynecologist was getting sick of his job and decided that he needed a career change. He'd always enjoyed tinkering with engines so thought he'd become a mechanic. So he went along to mechanics school and the final test was to strip the engine completely and reassemble it - obviously back into perfect working order. So our gynecologist friend did the test and anxiously awaited the result. The day he received the results he got quite a surprise, he got 150%! He quickly phoned the instructor and queried the mark. The instructor said "no no that's right. First I gave you 50% for stripping down the engine - - a very thorough job. Next I gave you 50% for reassembling it - a fantastic job really, and then I gave you a 50% bonus for doing it all through the muffler.

What rpm were you doing when it went bang?

What's a dual exhaust? Is that the factory cast manifold?

Didn't realize the car was in US. Photo shows RH drive so thought it was oz.

Don't forget the engineering requirements for registration. If you use an engine made before lead free laws were introduced, 1/7/86, you'll have an easier time passing the emissions tests. VG?

I weighed a long VG30et with turbo and flywheel but no clutch assembly, no alternator and no a/c compressor at 151kgs. That's reasonably light for a v6.

If you're running points ignition, check the spark, gap and whether or not they're burnt out.