He's talking about rocker studs. The stock studs would likely be fine with a 268H. With the XE series or a bigger cam, then you'd need to upgrade the studs. Stock rockers will also work with the 268H.
I also put several cams in SBFs before the aluminum head revolution and can say it's worth doing. Goodpoint on the screw in studs... I also pulled two or three pressed in studs back then. Just watch if you have the rail rockers that the rails don't contact the valve retainers with the new cam's lift #.
If the heads are E7s the don't have press in studs. And if I remember right there where some stock longblock fox Mustangs running in the high 12s, with dare I say E7 heads.
The studs shouldn't pull out. A 268H cam is not that extreme, and springs have more to do with studs pulling out then the cam anyway. Really stiff springs are needed for really high revs, but that is not your goal. Consult with your cam manufacturer about what springs will keep the cam in warranty and not stress the studs. It's very doable.
I'll second that assessment. With just a few mods to an otherwise stock 2 bbl 302 including the 268H, a Weiand Xcelerator and Holley 600 Vac secondary carb, my crappy 4 door '74 Maverick went from a complete woose to king of the road (well to me anyway) back in 1982. The difference was definetly noticeable in the "seat of the pants". The cam and 4bbl swap plus dual exhaust made about 60 HP over stock and except for the exhaust was all done in the parking lot of my apartment complex. A typical mid 70's 2 bbl 302 made a whopping 140 HP SAE net (at the flywheel) from the factory. It's easy to find gains when you're baseline is that low. That engine was also built with used but completely stock D0 casting 351W heads and exhaust manifolds, and made at least 200HP (of course I couldn't afford dyno time back then, that's based solely on my seat o' meter). Since you've already upgraded the induction and exhaust, I suspect the stock cam is more of a restriction than the heads, but probably not by very much.
The 268H is perfect for your budget and performance goals, but if it's at all possible try to scrounge up a set of early 351 heads. Just be aware you will need different head bolts or step washers, and may need different length pushrods.
I believe the push rods for 351w heads on a 302 are the same. Just use 302 pushrods. The headbolts will be different though. Unfortunately, making the 351w heads nice with all the machine work and hardened seats starts to get near the price of aftermarket heads.