'68 318 to carbed Magnum 5.2: Check my checklist

Yes, the roller engines were the preface to magnums...the 308 heads have the same pushrod pinch because the pushrod angle changed as soon as they introduced the roller lifters which shortened the pushrod length. There's actually a good bit of discussion of this within these forums. The 308 heads supposedly have really good exhaust ports too. The factory roller lifters in every roller engine I've torn down were very good at wear resistance. But if it makes you feel better, a stock replacement set should be available for about $125 or so...or you could pirate them out of a magnum as the part numbers to replace both roller LA and magnum engines are the same...you could also replace any bad singles with over the counter replacements. To be perfectly fair, that lifter-unless it's collapsed-is probably perfectly serviceable.

Now, all that being said, if you're going to the extent of rebuilding this engine because of the really low SCR, you need to define your goals first...what do you want out of the engine? Even a stock rebuild 360 with 8.5-9:1 compression, well built, proper cam and induction, will perform great and deliver years of reliable service...no special gimmicky stuff, no overly expensive parts, see also RRR's thread about hot rod bliss in the general discussion section.