winter time, nothing to do dumb question

on my 87' 48spl its about time to check/change the thermostat,(been 2 years in salt) located down by the lower bottom cylinder, a real PITA to get too. on the 89' engines they moved the thermostat to the top of the head. they both use the same head gasket, so i'm think'n same cool'n passages. Guess you see were i'm going with this, could i change the 87' to a 89' head? I know this a potentially expensive bad idea, but .....? just thrown it out there

Good question... I don't have the answer but it raised another thought with me. Wondering if the water passageways were changed on the powerhead (crankcase) also to compensate for the head design change.

Stick with the original parts and your better off. JMHO.

will stick with oem stuff. ordered temp gauge with "Z" bracket to mount on water cover,for piece of mind

update coming, just typed a bunch of stuff and lost it, this is a test

update - 1. after installing temp gauge and seeing 175 below 2500 rpm and 110 at cruse, that convinced me to change thermostat. also had a chance to speak with a guy that rebuilds these old engines,(showroom quality,lower unit to flywheel, everything with paint and decals, awesome) and he thought it would work. almost completed just waiting for shorter head bolts. but did find a couple of small scours in one cylinder wall. before starting did compression check and got 140 -142 on both holes, was 148 when bought 5 years ago. As of now going to reassembly, test temps with heat gun at startup, if it looks good, then a heavy seafoam treatment, and check compression often. any suggestions about scouring?
2. so with 1990 head, got a 90" manual and it says to apply a thin coat of OMC gasket sealing compound to both side of head gasket! i know on this forum its been the general rule that head gaskets don't need sealant, and say so on gasket. so what to do? 87" manual says nothing about compound. any comments? hope this doesn't start a debate like 50/1 vs 100/1 amsoil, but lets see

over due update, 1990 head on for awhile now, all running normally, low RPM's temperature drops now around 1200 now, compression still above 140 both cylinders
as noted before the manual had instructions different from common procedures recommended on this forum, again i found something that's been discussed a lot here, and may stir the pot on differing opinions, i've done compression checks both ways and always get same results, BUT the 90' and 87' manuals read like the following;

2. Compression check - Proper compression is essential forgood engine performance. An engine with uneven compression
cannot be properly tuned.
• Operate the engine until it reaches normal operating
temperature. Stop engine.
• Remove and inspect all spark plugs. Check their
condition.
• Install thread -type compression tester in spark plug hole.
• With throttle in wide-open position, crank engine with
starter through at least four compression strokes.
• Variation between cylinders should not exceed 15 psi
(100 kPa).

really enjoy this forum