340 Running super weird

Sorry I haven’t responded to anyone, so let me give a little more info on the set up, I’m very familiar with the car as I built it myself, it’s a 73 cast crank 340, with a cam intake and carb and that’s about it, nothing fancy, the distributor is a stock style electronic distributor, I swapped that spring back to the way it was and put the advance limiting plate in the 18 degrees of advance slot and set the initial at idle at 16 degrees advance, with the timing light on it and getting the rpm’s up to around 2500-3000 it’s going beyond 34 degrees total timing. The vacuum advance is blocked off, I’m not using it, and the issue is still there, I have undone everything that was done by my friends so I think next weekend I’m going to do a compression test and a leak down test and see what I come up with there. I pulled the valve covers and took a look and everything looks good, no bent pushrods, it has stock stamped rockers. I’m getting a little concerned that whatever the issue is that it could ultimately hurt the 340 and id hate to toast a 340. One quick note, when I first purchased the advance limiting plate I set it up wrong(or maybe right since it ran good) I put it on the 10 slot and set the timing around 15 degrees initial, so maybe since it allowing more advance that worked out setting the advance up lower back then. I’m super lost here guys and I’m sorry for lagging on the replies, I greatly appreciate everyone’s input and I’ll do my best to get back to any questions or info yall need, I store the car about 45 minutes from me so I can only work on it on the weekends.