I would suggest adding the 1.6" exhaust valves. They are standard small block parts and it won't cost anymore than a stock valve. On our air flow bench we picked up 34 cfm at .500" lift, and that's a bunch of cfm for not much work.
Watch out when working in the intake side. Those lump ports do work, but read at what rpm they are using them. I took modeling clay and added to the intake ports to match the lump design. I did not remove the center divider. The air flow stayed just the same from .050" up till .300", at .005" it was higher, 190.5 cfm with clay, 168.5 stock.
For steet use you want great low lift air flow with a high volocity air speed. To get that you need small well designed ports. The open lump ports are to big, it takes to much rpm to get the air moving threw them. The guys running them are only using a small range of rpm, 6000 to 8000.
I wish we would have measured the port volume on my head before I put together. I used a high heat epoxy and filled in were the clay was. It wraps around the center divider and tapers down to the back of the bowl area. I used porting tools and sandpaper to work it. I would bet we closed off 1/3 of the port and still kept the same flow, which means better throttle responce. It feels really good off idle even with a 3.08 gear and 28" tires.
Your HEI should be strong enough for this type of engine. Dad also has a distributor machine and we have spun HEIs to 7500 with out having them miss or jump around. I just regaped my plugs out to .060" and improved the idle a bunch.
You should invest in one of the computor engine analyzers. You would have a lot of fun with it. I use the Performance Trends base model, and dad uses the Pro model. You can spend hours changeing stuff :p :p Joe
