33 GTS4s look the same as a 2 door GTSt, and they also came in 4 door sedans
Another thing to remember is that since they (GTS4) are non-turbo, they will have the 4-stud hubs and GTS brakes, meaning if you want to swap an RB26 in, a brake upgrade would be needed (brake upgrades are required here in Vic if you want to swap another engine in anyway, not sure about NSW)
You might as well swap the gearbox/diff and possibly the ATTESSA system as well~
An RB26 swap into an R32 GTS4 would be heaps cheaper and far more simpler and straight forward, because the drivetrain is basically the same as the R32 GT-R's..
Nissan fact: After seeing alot of their R32 GTS4s being upgraded to RB26 making a cheaper GT-R, Nissan changed the drivetrain in the R33 GTS4's and made them non turbo Same thing could possibly happen to FPV with their F6 Typhoon, being very similar to the Ford MkII XR6Ts, an ECU flash from the Typhoon and a bigger intercooler fitted to a MkII XR6T would make it a Typhoon on the cheap~!