[blykins]

Don't worry about the china wall gaps unless the ports don't line up. That's the most important thing. Borrow a bore scope, take some measurements, etc., but port alignment is most necessary.

If the ports line up, just have the valve cover flange milled to make the valve covers seal better, and lay a good bead of silicone down. In the aftermarket world, that's how it's done about 99% of the time.

A hydraulic roller will not offer any more performance than a solid flat tappet. The only thing it will offer is a 100% surety in camshaft break-in. Other than that, it's a pretty expensive upgrade at this point.....$400 for a custom camshaft, $425 for lifters, $65 for a distributor gear, $125 for valve springs, $125-200 for pushrods, and some expertise to set everything up. Also mentioned earlier, if it's a solid lifter block only, he won't have a choice.

I can offer a more appropriate solid flat tappet camshaft that would make more hp/tq for the same manners, but it's stupid easy to just jam the same stick back in if he's happy with it. Most guys don't drive 30000 miles if they're not happy with the engine's performance.