72 360 first start question

You can't make any conclusion that having the cam timing off would not show an engine change with a change in carb.

Fuel pressure gauges are cheap. A lot cheaper than a dial indicator. (A dial caliper will work and is a lot cheaper than a dial indicator.... see if you can borrow one.) You need get/borrow a timing light too.

Connect that vacuum gauge up to the manifold under the carb and see what you have.

What cam do you have? (I ask this as it relates to what you may expect on the timing check.)