Well, a .030" overbore combined with the 4.5 crank will give you a 545 cubic incher...plenty big to make great power & torque.
Your plan sounds good, build a strong shortblock, then upgrade the top end later.
The only thing I'd do is go with a bigger carb than a 770 CFM, as even the unported D0VE's can fit a little more thru them, although the cam you are proposing will be very mild in such a big displacement motor.
Also, the 1-7/8" headers will be a restriction with the big displacement, I'd move up to at least a 2" inch primary, but they'll work for now.
Your plan sounds good, build a strong shortblock, then upgrade the top end later.
The only thing I'd do is go with a bigger carb than a 770 CFM, as even the unported D0VE's can fit a little more thru them, although the cam you are proposing will be very mild in such a big displacement motor.
Also, the 1-7/8" headers will be a restriction with the big displacement, I'd move up to at least a 2" inch primary, but they'll work for now.