426 hemi info : new to big blocks

looking to built my 70 hemicuda as a driver , street and highway use , and a 5 or 6 speed with 3.54 dana rear end , oversize to these huge amount of bore size it will not affect anything since theres a lot of material? , and it can be bored and stroked without a problem of overheating of reability ? Jeez 4.25 to 4.500 isnt like 0.0125 over ??? Looks like something that isnt worth it, no ?