I believe the 270 cam that is recommended for a restricted combo is the one with the 110lsa, and is not split duration.
aka Comp Cams xe270hr p/n 420-8 - spec's = .533/.533(1.6), 270/270, 215/215, 110.
I disagree with your Dad. On a little 200cfm combo with 140cc intake ports and small valves, an aggressive cam is the only way to extract every last bit. More money, yes, but with that both performance and driveability increase. I went custom from Buddy Rawls and have a ported stock combo that has no dead spots, no surge, no lurch, pulls stong below 3200, and hauls along very hard to up over 6100... this with the stock electronics, no fancy chip/tune or tweecer type stuff... even has the crappy C'n'L that is a waste of money...
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Will the Tmoss run out of juice? Dunno, seems to be some debate on what Thumpers heads flow. Neat thing is, a good custom cam based on all the facts would be able to work with a restricted intake... which is precicesly why I went with Buddy R. He has a lot of experience spec'n out cams in restricted combos...
I would run Ford rockers... er, I am running Ford rockers.
That 12.9 was in 2600 d/a conditions, so, figure 12.6's at sea level, and that is with the stock ~140cfm lower... I don't think I'd get too wound up about Toms lower being a hold out in the ET department.
As a matter of fact, I feel strongly enough about that, I'm currently ditching my Holley Systemax 1 lower in favour of one of Toms pieces of handi-work.
Best of luck with your budget stocker project.