in the last month I have driven two of Keith's big block motor, both in Cobras. Coach Mike's 428/461 with 601 hp & 619 tq in a Hurricane TKO 500, 3.25 nine inch. Lainhart's 427/487 with 618 fhp & 638 tq in a Unique 3550 3.31 Jag rear end. Both car run smooth at all speed. They are a pleasure to drive. Lainhart'a will cruise at 1800-1900 range but Coach's like 2000 or better. I have rode hundreds of mile in Coach's Cobra but drove it one time last week. I have driven Lainhart's Cobra for 150 miles plus on 5 or 6 outings. From 50 to 130 in seconds!!!!! 15 to 100 quick and easy. I have not put it to the floor yet. I have changed the name of Lainhart's Cobra from Satan to Sweet Monster.
Long story about us naming it Satan.
I think patrickt's advice for the 3.54 rear gear ratio is something to think about. Don't forget tire size as part of the equation. If you are going to do a lot of cruising at 70 mph then look at the mph charts/calulators to see what rpm your combination will give you at that speed. If it is below 2000 rpm then change something, tire size, rear gears.
I'm very impressed with Keith's motors. Call him, tell him want you want to do with your motor and he will built it. If you want to build your own motor, let Keith do the heads and pick a cam for you. You will be happy.
Double Ditto on Fkemmerer's post
Dwight