i have compression tested many srt6 engines COLD and they have been 145-170psi range, the NA motor is a HIGHER compression motor and thus should make more PSI on a compression test, i would expect to see 170-190. yes there is % that they need to be within from each other, but all being low in the 75-100 range is no good, if the test was done with good battery voltage and a good gauge and know how, then the engine is doomed, figure 250 for a used low mile motor from a junk yard and 10 hours + fluids for the install.