Need New Engine!

[caliplaya650]

My car has 170,000 miles on it and is leakin oil i believe where engine mounts to the tranny. And for about a week now the car has been pinging really loud i can have the music up and i can clearly hear it. It pings really hard at 1500 rpm and pretty much doesnt stop till i either come to stop or i turn off the car!

Which brings me here. What should i do?
1)THere is a guy here in my town that has a 68 302 w/ 4000 miles for 450 o/bo. Would it be able to fit in my 92 gt 5.0?? would it still have the performance of the 5.0 i have right now?

2)I just called schucks/kragen/checkers and the better of there two engines short block is 816.00 w/ my core.

I will try to contact a place here that sells used engines and see what they have to say.

If you have some input please POST!!!!!!!!

ALso i talked to a guy who owns a tow place and he has a 92 stang gt that was rear ended pretty bad for 1300. The car besides the rear end collision is in extremely good shape. the interior is practically new. Every interior piece is in tact. Any ways he told me that the kid who owned it died in the crash but that he had taken the engine to get rebuilt by some1 who built racing engines. I took a look at the blue paint didnt look old at all im just not sure how i would tell how many miles it has on it and if there are any papers. Do you think it's a good deal? The only thing i have a prob w/ is if i were to buy it what would i do w/ everything extra?