Definitely gonna want more stall( lots more) than 4,000.
THIS^^^^^^^^^^^^^
If the heads only flow 297 you can’t get enough cam in it to shift at 8000. You are induction limited.
I’d put the roller in it, get it on the pump and see where you’re at. At that displacement with the roller you posted I doubt it will make power past 6800.
EDIT: that 104 LSA will tighten peak TQ to peak HP. A lot. And that extra exhaust duration is to try and get it to RPM that high.
IMO, I’d not try and save money and buy something else. On alcohol you only need a 4 degree split on duration. The exhaust port will take care of itself.
Again, my opinion is you should be 274-278 at .050 on a 109 LSA with as much lift as you can get up to about .750ish. The love gear will take more lift than that, but it gets sketchy if you don’t have everything dead nuts on, and the gains above that lift won’t make enough of a difference to matter.
BTW, you can’t get the pushrods too big in diameter or get too much wall thickness. IMO, you should have a 3/8-7/16 double taper pushrod. I’ve run straight 7/16 pushrods, but the taper gets you some extra room on both ends.
