When I looked at it, I remeber it saying the ECU must be "from the period". So that pretty much limits you to the stock ECU or maybe there were some very early Haltech's, etc about then?
There were also a lot more freedoms with fibreglass panels, intercooler, turbo, injectors, etc if the car was built in 1981 or before. I think the first 280ZX Turbo was built in 1982? I know they've changed the classes for the new historic tarmac rally championship class so it's probably all changed since I looked at it.
Anyway, back to the subject sorry navanskyline. As the others have commented, it sounds like your engine has had a bit of work done so I'm guessing it has had the head shaved and/or flat top pistons. If this is the case then your compression ratio will be too high.
Better to sell your engine and get an n/a engine from a 280ZX. It will have a comp ratio of 8.2:1 and happily take around 10psi on 98 fuel. With decent manifolds, exhaust, computer, throttle body, intercooler, turbo, injectors, fuel pumps, etc, etc, you should be able to make close to 200rwkw on standard internals with good reliability.
Unless you can do pretty much all of the work yourself then it will cost you a small fortune.