Could you share some of the issues that you have encountered?
Sorry, I missed this on my last read through.
Initially had had to do the usual new Marlin clean up of sharp edges rough action etc. The lever from RPP needed a fair bit of trimming at the tip (lever image circled in red) in order to function. The factory lever left a faint wear mark on the inside of the receiver so I suspect that the receiver is out of spec. When I installed the RPP peep I used the forward mounting screws and accuracy that should have improved went to shit. This is when I figure out that the barrel is loose.......I removed the mag tube and could unscrew the barrel. When hand tight it's over clocked by a few degrees so who ever assembled the rifle lined up the top flat with the receiver and then used the front scope mount dummy screw as a set screw to hold it in place and sent it on down the line. I sent it back and all they did was add a shim and re torque the barrel......now I've gained an extra 0.003" of headspace. Interesting thing is it will drop the hammer with a "no go" gauge inserted even though it's not fully in battery. The mag tube follower was also hung up when I got it back and you'll see in the picture the lovely mess they left when the peened the shim up against the barrel to allow the mag tube to fit in the receiver.