In agreement with everything stated by Scott and Gator, and would only add the following.
Bonkers... Your explanation of exactly 90 psi compression in both cylinders (if it is exact) would indicate a failed head gasket between the two cylinders which would allow the compression to criss-cross, for lack of a better word, from one cylinder to the other... commonly caused by not torquing the head bolts in a specific manner. The result is close to having the engine submerged, and to put off proper repairs until later is to invite a rusting problem which begin immediately.
At a minimum, carefully clean the surface of the cylinder head and the block, install a new head gasket and torque the head bolts to their specified setting (service manual) in the sequence below whereas each number represents a head bolt.
9...10
5....6
1....2
4....3
8....7
And be sure to tighten all the other bolts, nuts, screw, on the powerhead as being "that" hot, they are surely loose. The gaskets of the exhaust baffle plate may also need replacing... but... you may be lucky in that department. Time will tell.
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