Re: Dennis Moore's thoughts on heads
I have the book, but will not sell it. I'd gladly share what it has on head recommedations, but the book is 3 hours away, and won't be able to check it until Labor Day weekend. :'( The good news is that many others that follow the forum have it as well, and you will probably get the answer before I can provide it.
He does provide specific guidance based on what heads you have and on other modifications to engine. I don't remember the specific guidance for your year heads. In general, he recommended cleaning up the ports on most heads. He also recommended going to larger valves. I wouldn't go there unless you are building the rest of the motor to hit higher rpms above 5K, and have a much freer flowing exhaust.
I do remember Dennis liked the '87-'96 head better, because of the relocated spark plug and he considered the '96-above vortec head to be the best production engine head available. Going to either of these heads, requires a new intake manifold. The '87-'95 has canted center bolts, and the vortec has taller runners and no center bolts.
If you have flat-top pistons (w/valve reliefs) vortec heads will put you up in the 10:1 compression range. Might not be an issue for you, but expect to be buying premium gas only. If you have the dished (smog) pistons, then the compression is about 9.5:1, which is the same as current marine 350s. Also given its an '85, probably not worth it unless the rest of the bottom end is fresh. Also make sure your drive condition will be up to the added hp. Before going vortec also make sure it will work with your cam, which I believe is standard hydraulic lifter, not roller.