We're still running cams about that size, and no, we've never cut down the valve guides. You figure, .750 is about 3/4 of an inch, and the installed height of a Hemi spring is roughly 2 inches, and you'll be fine. Now, we have never used valve seals, most don't for racing applications, so have never run into that. If you are concerned, take the spring off, hold the valve and retainer together, and lower into the guide about 3/4 of an inch. You will be fine, I'd almost bet the ranch on it.

Just be sure to check piston to valve clearance, but if the pistons have reliefs in them you'll probably be OK there. In the old days, with stock pistons, .650 was getting pretty close. Check your spring when compressed and make sure you have no coil bind, but, I don't imagine you will have any issues there, either. But, check it anyway.

But, my thought is that everything will clear just fine.