1. Port the stock heads. Reasons why appear here. Keep the stock valve size, but make sure they are backcut.

2. If you want to go with a roller lifter then get the entire set from a junkyard Caprice/Roadmaster/OldsCustomCruiser wagon, in any year from 1989-1996. I say wagon because they are probably well maintained; any other TBI v8 car will also have the same roller lifters but more questionable maintenance.... especially a copcar Caprice.

3. If you stay with flat tappet, I suppose you could use a new cam but I would not stray much from the stock specs, because you will gain a lot from the head porting so you don't need a hotter cam. Especially if part throttle performance, and towing, are important to you.

4. If you go with roller lifters, use the 1994-1996 Caprice LT1 camshaft; this is also the one used in 1996-1999 Vortec L31 engines. It's perfect for a truck application, and it was good enough with the iron LT1 to make 260 fwhp and 330 fw ftlbs.

5. Keep the TBI. Port the intake manifold, especially the lower plenum runners (lower plenum don't flow as well as the upper).

6. Try to add the best dual exhaust + low restriction cats you can find. This coupled with an engine that breathes really well will make an awesome street/towing performer.

7. Make your own ducted cold air filter. See this thread for ideas:

http://impalassforum.com/cgi-bin/ult...c;f=9;t=001945

See this thread for general info on TBI engine mods/maintenance:

http://impalassforum.com/cgi-bin/ult...;f=33;t=009021

FYI, your existing LO5 engine was rated at approx 210 fwhp and 300 ftlbs. You should be looking at 270-280 fwhp and 350+ fw ftlbs if you do the above. HTH.