Re: compression readings 1971 1350
It's quite a bit of work to pull the exhaust manifold cover since you'll need to remove the powerhead to gain access to the bottom bolts.
Once you have removed the exhaust manifold cover and baffle, you'll be able to see into the intake ports and have a pretty good idea of the condition of those 2 pistons (and the other cylinders, too). You can also remove the upper intake (transfer port) cover for inspection.
If the rings in those cylinders are free to move when gently pushed with a soft implement, you might be able to run it for a while. If they're carboned up, a Seafoam treatment might help.
If the pistons are scuffed-up/scored and the rings are stuck due to physical damage, nothing short of an overhaul is gonna fix. You might get by with running it a bit but keep in mind this will only damage the cyl's further and send bits of worn metal circulating.
While you're inside the Beast, be sure to check the water jacket cover around the exhaust ports. It's also a known Leaker, in addition to the exhaust baffle. You may get lucky and just find old, dried-up gaskets but you never know until you get in there.
And watch out for reluctant bolts, if this motor is a Salty Dog you're gonna have Lotsa Fun getting the side cover bolts loose! Use Plenty Heat (pick up a MAPP torch from Lowe's, Home Depot, etc) and if a stainless bolt breaks, you're looking at a Heli-Coil repair. If the bolt won't move, drill out the bolt head then use Vise-Grips on the remains after you pull the covers.
HTH & G'luck with the repairs...........ed
