Recently purchased 95 240SX.. Got some questions

[pinoi007]

I purchased a 95 240SX with 125000 miles on it a few weeks ago. My cousin and I did a compression test on it and the numbers were 150-149-139-141 across. I know those are the minimum specs or lower and Im not burning any oil. We tested one hole with oil and concluded that it was the valve. I know I can't turbo this engine without a rebuild but I was wondering

1) how much to rebuild the entire engine and what parts are going/needing to be fixed so it will be strong enough for a turbo

2) Also, with the car being daily driven, how much life does it have left so i know what to expect in the future so I can prepare(save up) for it.

I have read that rebuilding the engine will cost as much as swapping a SR20. Correct me if I am wrong, but I read that KA-T will be more powerful than stock SR20DET but the SR20 has more potential?

Finally, as for now, there is a rattle in the middle muffler connected to the intermediate pipe when the engine is at around 2k RPM. I was wondering if there is something inside that can make the noise and if so, if it can be fixed w/out buying new/used parts.

Below is a pictorial view of the location of the exhaust problem:

==[ ]===[ ]====[ ]=
^
Noise.

The brackets are the mufflers.


Please dont flame a NEWBIE. I have read alot before posting this. Any help/suggestions/opinions will be good. Thanks.