you have more chance of mig boys helping you out instead of Courtenays,the buch on here are more knowlegeable.
The gearboxes are easily mated up,should be no probs,same with engine may have to find/make some custom hoses but Turbo-chris can make you up a custom set for a lot less than Samco etc.the exhaust manifolds can be bought to stick a turbo,d engine into a Nova so im sure you could either fabricate one or get it made for you.
Vauxhalls are one of the best makes for get the spanners out and stop worrying!