That is one take out of this conversation. Just make sure the chambers are opened up. I would be having them CC the heads if you don't want to do it yourself, and open up the chambers to beyond 74 cc's. I would prefer to have them pretty well equalized too.
At that, you'll still need to run a higher duration cam than would normally be picked to run the car like you originally described. But, the pistons as installed set that limitation. Something like the 308 is not a cruiser cam at all; I'd expect it to be mighty lumpy at idle, and fer sure require a higher stall TC. Now for the valvetrain to support the cam.....you need to look at the rocker and valve guide/retainer clearance to be able to handle the lift associated with the larger cam; some bone stock heads will probably need some retainer clearance work.
So it is not just a matter of some plain stock heads with large valves tossed in at this point. If you want true off-the-shelf, IMHO you might be well served to speak with someone like Brian here, who will cover all these bases for you as a complete off-the-shelf package of cam and heads and valvetrain. (And I don't mean to speak for you Brian, so just tell me if I am overpromising for you LOL) I don't normally do this, but there are enough details here that need attention that this approach seems like a good one in this case, assuming it will get done to your timetable.
The power brake vacuum may be best solved with a separate vacuum pump. But, seriously, if you want to dispense with the power brakes and not let that be a constraint on the engine operation, there are way to get more brake torque without power brakes, especially in a lighter A body. If you have large read drums, then higher coefficient of friction pads up front, like EBC Yellowstuff pads, will make the fronts have significantly more brake torque for a given pedal pressure, and any prop valve in the rear can be backed off to let the rears produce more brake torque too.
