The avionics tickle me. Immediately the buyers start thinking of a big panel upgrade - yet the pilot(s) flying packages in this airplane flew the wheels off it for 11,000 hours in all kinds of weather that the new owner would never dream of going out in, with that panel.
A fancy panel does not a pilot make.
As far as a cheap overhaul - it all depends on total time and condition of the injection pump and injectors, accessory case, oil cooler, vacuum pump, hoses, plug wires, engine mount, is prop run out, muffler and heat muff condition, any ADs, yadda yadda. This stuff can double the price of just doing a field overhaul of the basic engine.
Plus it is likely you will find that all the controls need new rod ends, etc. to get the slop out of the yoke and pedals, the door hinges and latch are worn out, pilots seat track is junk, and so on.
If you can do the work and have access to the parts at distributor prices maybe - just maybe.
I get all kinds of young guys fascinated by my Fat Albert The Apache (1957 PA23-150)
One even came out and said "boy, I'll bet that is cheap flying"
My comment back was, "If you can buy one cheap you can't afford it."