JMHO, sorry don't mean to beat a dead horse, but low vacuum with other symptoms points to valves.
The most common mistake with setting valves is HURRYING. You must take your time. Get the valves positioned correctly for the cylinder, loosen the rockers completely and let it set a few minutes to allow the plunger to completely rise.
Second most common mistake is FORCE. This is not a strong arm procedure, you do not want to use force. It's delicate, you just want to take the slack out without compressing the plunger spring. If you compress the plunger spring even a little your valves will be too tight.
Third most common mistake is ALIGNMENT. Get the positions correct, close doesn't work here, especially with a upgraded cam (even more so with tighter LSA).
Not trying to be mean or disrespectful, but, IF the valves are too tight (I suspect they may be) and you continue down this present road, you will cause an expensive repair (if it's not to late already).