Wow great colour - dont see too many of those. The gearbox is a limiting factor as is the engine - closed deck block or not. I wont quote figures as I am not as familiar with the classics as others on the forum are ( @Tidgy@savage bulldogs ) you can get reinforcing plates for the gearbox though and cross hatching on the block will tell you if it is a CDB or not.
In order to do do the map though check your ECU to see if it is standard, not ESL modified or aftermarket Alcatex etc otherwise you will not be able to map. So I would check that first before turbos, injectors, clutch and the rest.
Savage has a thread going that started in the same way your post has..... Plenty of information in there, food for thought etc including an Arashi turbo unit which could be an alternative to the standard TD options?