Is a Holley 750 DP too much carb?

Yeah those tires are for slantys. But the height is close at about 26.4 high; which calculates to 83.4 in circumference. All my calculations were based on a 27.0 inch tire at 85.0 circumference. So that is within 3.2%
Most As after 67 will accept up to 28 inch tire, which is a 275/60-15, which is about 6% bigger. You can accomplish nearly the same thing with the next size down gears,3.73s which are about 5% shorter.But since the 26.4s are waaaay to skinny for a 360 anyway, a new higher tire is the way to go, and especially wider.
It's not stated I don't think, what car you have and that makes quite a difference in tire fitments.EDIT, I found it's a 70Dart.
A 5-speed is absolutely the best thing for a Normally-Aspirated SBM in our As. There is no question about that. The trick is capacity and money; they are not cheap! And they don't all drop in, so there is more money to install one.And one with a big enough capacity to survive a stout 360 is even more money.You can buy an awful lot of gas for the installed cost of one of those bad boys.

Now if a 4-speed automatic was on the table........