Most of the slant's power potential is in the head. Porting/bowl blending/gasket matching will all make a very noticable difference. Bigger valves help as well. Ford 300 valve are the correct length, but have narrower stems than the stockersso they need to be re-bushed (no big deal if getting the head redone anyway) The other major head consideration is what compression ratio are you looking to run? You can safetly mill up to .100" from the slant head AND block. You will obviously need some measurements to calculate it out, but on the average taking around .060 from a stock head will produce approx 9:1 compression, .100 off a stock head will give around 9.5:1
If you decide to do business with Clifford, make sure to do it over the phone. I have heard nothing but problems and horror stories about their customer service since Jack left. I would also not consider anything but headers from Clifford (comparable/better cams, intakes, carbs, etc can be found for cheaper)
Intake options include clifford, offy, weiand, and the factory supersix setups. I highly recommend an offy 4bbl intake (JCWhitney sells them). You may also want to check out a relatively new dual weber 2bbl setup. I have not tried it (yet), but have heard nothing but praise. Check it out at
http://www.prolinefuel.com.
Cams--as always, depends on what the use this slant will see. Comp Cams has several solid and hydraulic grinds.
As was said earlier, put an MSD ignition on it and you will never look back.
There are several "build" options for a slant. We need to narrow down exactly what use this slant will see, and build it accordingly.
FYI--the slant in my sig is going to be a street/strip motor. I just rebuilt it to what
should be pushing about 225+/- HP and 300 +/- Lb-Ft, the track will tell all this summer (and a dyno run if I ever make it down to Anchorage this summer)
-SM