although low on compression, if the oil doesn’t raise the compression it could be a blown head gasket or a burnt valve, one other thought could be a cracked head.
If the gasket doesn’t have a darker streak on it or on the metal parts, then check the valves how do they appear to you.
Since you have the engine apart, maybe see about a valve job to include a head cleaning and magna-flux (sp), magnetically checking for cracks in the head surface.
Sometimes the cracks in a head will only show when the engine is heated up and having the head checked is the only way to know.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter