Definitely do the cam seals while you're there, and replace the spark plugs if you haven't already.

The space available to fit a valve spring compressor around the valve springs is ridiculously tight on your engine, and 99% of the valve spring compressors just won't fit. Unless your buddy who owns the shop has used his spring compressor on this motor specifically, I'd lay money on it not being usable.

95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes