prolly go aftermarket managment like the greedy emanage, thats 700 plus 100 for injector harness. Workshops charge alot of labour if u can do stuff urself u would save lots of money but ill give u some ruff estimates.
rb30 bottom end say 400 from trading post
500 bucks to get that matched to ur head from a workshop that has done it before
1000 re grinding ur cams
800 porting
extractors would be off the shelf items modified to a slightly larger exaust, 3 inch would probably be a bit big id look at 2 1/2 so 250 for extractors 100 bucks for cat, bout 600-800 for mandrel bent car back
nepod filter and a nice piece of polished pipe to go from the intake manifold 200 bucks all up including placment of the pod in the front bar for true cai.
approx 1500 for greedy emanage install and tune.
Total Approx 5350-5500 and that would be one sweet engine minus a few more things like balancing the crank more dollars and lots of labour and possibly raising the compression slightly and maybe multiple throttle bodies. those would be the few things left without getting into super big dollars.
It would be very hard to estimate what sort of power figures could be achieved without actually doing it but for arguments sake this was going to be my engine (listed above plus forgies for big gas) but i went with the v8 to be a bit different. I would say with good few over 200kw's at the crank would not be un achievable.