Hey Bevan, good option!
The RA40 should be easier to find parts in any unfortunate incidents.
I've never built a car from scratch, so i'm just throw suggestions out there.
1) make a members ride thread. I think that's more appropriate for your buildup that the tech/conversions sections.
2) 18RG should be good. For a track car you don't need massive poer to have fun... but you do need a free revving engine. nothing better than an engine that progressively pulls to 8k rpm, even if it is only pulling to 90rwkw
3) make it reliable. everything you do, make sure you spend the time to do it properly. Spend the time do wiring properly, planning mods properly, planning maintenance properly. No points rushing to get some u-beaut new guages in quickly, only to find the twist-tie you did on the wires shorts out and blows a fuse, ending your $150 track day after 5 mins!!!!
4) have fun with a reliable, safe, light, and relatively semi-stock setup. Work out the deficiancies, and go from there. You will probably find that the first thing to upgrade is the brakes. Then the springs. Then the tyres. Then the shocks. Then the geometry. Then the power.
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