High Mileage Magnum

So, I have been searching for a 360 Magnum to drop in my ‘65 Valiant. There are plenty of old Rams for sale around where I live but they all have very high miles on them. (200K to over 300K) Today I went and looked at one that is for sale on the side of the road near my house that I have seen for sale for a really long time. I looked at the odometer and it read 286,000 miles but I went and knocked on their door anyway. The truck looks like it has been very well taken care of; the owner started it up for me and the engine runs beautifully. Becides the torn/cracked interior pieces it looks like a well maintained truck. The guy said that he bought it new in 95 and is only selling it because he got another truck (exact same truck just a bit nicer) He’s had it for sale for over a year so I think I could get a pretty good deal on it for the engine and just part out the rest. I have a friend that could recondition the heads for me at least and I know a really good machine shop that could do a full on rebuild to new if I want. Would this high mileage engine be a good route to go if I want to keep the cost down? Like I said, almost everything available where I live has high miles but this one look like it was well taken care of.
I plan on converting to carburetor set-up and doing a few small things to the engine.