Engine Decisions...Fix, Rebuild, Replace???

[Longhorn 70]

I have a 70 Longhorn with a nice body and chassis that I have owned for almost 30 years and it was my deceased Uncle's before I bought it. It came with a 350 4V and a T350. When I bought it, a manual with granny was in it. Now it has a 67 Olds Toronado 425 in it that I rebuilt 25+ years ago that has a lot of miles on it. The olds still runs but is getting tired. There is a slight, low knock in it and the oil pressure fluctuates with the knock...... I really like the smoothness and power of the Olds but don't like the costs associated with rebuilding it.

I am going to pull the motor this weekend and mic the crank main and rod journals. I will also verify the connecting rods are the proper size. If all looks OK and is within spec, I plan on replacing bearings and oil pump and bolting it back in. Besides the aforementioned, I will replace the rear main seal and front crank seal. As well as the front transmission seal.

Anything else I should do while I am in there??? I feel I am forgetting something. OR should I bite the bullet and rebuild the whole thing? OR, again with the ORs, should I replace with a small block and be done with it???

Thanks in advance for the voices of reason and consideration.