Okay, so here is the comparison of a TB42E and the RB26DETT. My motor is the TB42c which I couldn't find a power figure on, the TB42E would be making more power than my tired old Carbi clunker. When I get it back from getting the diffs built I will put it on a dyno and see just how little power it is making, I know that the heavy 35" tyres wont help the figures but it will be good to see just what I'm playing with.

TB42E and TB42S
In 1992 the TB42E emerged with electronic fuel injection and electronic ignition. At this time the TB42 was re-labeled as TB42S. OHV
175 PS (128.7 kW; 172.6 bhp) @ 4200 rpm
32.6 kg·m (320 N·m; 236 lb·ft) @ 3200 rpm

The first 2.6 L RB26DETT featured twin-turbochargers and produced around 280 hp (206 kW) @ 6800 rpm and 260 lb·ft (353 Nm) @ 4400 rpm. The last series of the RB26DETT produced 280 PS (206 kW) @ 6800 rpm and 289 lb·ft (392 Nm) @ 4400 rpm. } The reason for this discrepancy is a gentlemen's agreement between Japanese automakers to limit the advertised horsepower of any vehicle to 280 PS (276HP). It is widely known for its strength and extreme power potential. It is not uncommon for 600 hp to be achieved without modification of the engine internals. With regular maintenance, many of these engines have been driven well beyond the 100,000 mile mark with a few heading toward 200,000 miles. With extreme modification, the RB26 motor is capable of power in excess of 1 megawatt (or over 1,340 hp).

As you can see the TB42 makes (128.7 kW; 172.6 bhp) @ 4200 rpm, (320 N·m; 236 lb·ft) @ 3200 rpm and the RB26 makes 280 hp (206 kW) @ 6800 rpm and 260 lb·ft (353 Nm) @ 4400 rpm. I know the RB makes it's power at a higher RPM but I don't think it will be an issue considering the TB42 redlines at at 6000 rpm and I do spend a bit of time on the limiter .