How are these cars compared to newer cars?

[The Deuce]

Since everybodys throwing out ideas, the New cammer motors are as wide across as the old big blocks. So if you want to go with a 65-66, use a 351w, like above.

I've heard but never seen, that the new Cobra IRS bolts up fairly well to the pre 69 cars. Mr Shelby was once seen running around in a 64 falcon with IRS, as it was considered for the orginal mustangs.

The 302 and T-5 will bolt right in, but you mentioned wanting newer stuff. Figure out what you would like, see if it can be done, then if you can afford to get it done.

In the end its your car, so do whatever you want. Just know there will be purists who cry over it if you get too modern or different.