Automatic to 4 speed Conversion in '65 Formula S

I will say, my HP273 in my 66 isn't much more than stock. I did advance the valve timing a couple degrees for a bit more bottom end and I could use some 901 Comp valve springs instead of the short, shimmed, up E bay springs I have in there now. The engine wouldn't run out of steam at 4500 rpm if I would make some changes. I have the original 833 in there as well as the original 3:23's. I shot myself in the foot by installing a a pair of 225-70/15's on the rear. (for looks) I am not a clutch side stepper but once I get her under way she pulls you back in the seat pretty good. First is a fairly short gear but second is my power gear. I need to pay closer attention to the rpm and mph of my shifts. 3rd is surprisingly powerful as well and by that time I am at 75 or so and time to shift into high gear. I am real happy with the 1966 833 and the 3:23 gear. I would need to degree the cam and get some better valve springs in her to be able to take advantage of another 1000 rpm or a 355 or better rear gear.