Connar... You can get the S54 ITB's which are more readily available and there are a few companies making adapter plates.
Then if you want, you can get cams that are close to the Schrick 256*. That's what I have, 250* with 10.3mm lift vs 256* with 10.4mm lift. The 250* cam is more aggressive. Contact Dick Chiang at Dynospot racing in California if you're thinking about the Schrick cams.
That should definitely give a bit of a punch with cams and ITB's. As far as HP goes....it's more about the torque really. Get a good torque curve and you'll always be moving forward quickly. LOL Lots of HP on a dyno sheet means nothing. But I know we get caught up in HP numbers to get a standard of comparison. So I'll take a stab at it....stock motor with ITB's and 25x-ish cams with the right tuning should get you in the 165-170 crank HP area. If you have the proper tuning it could be even more. Just a guess though. If your tuning isn't changed, well.. then you might not get to that number. Hahaha
Just remember that changing the top end, say cams, will only move your power band higher in the rpm range. If you want to have more torque then you'll need to change the bottom end.
Cheers,
~Ralph