but like mentioned, that stock block is a grenade with the pin 1/2 pulled. I have two friends that know personally what happens to them. It's not "if", it's "when".
Friend ran his factory shortblock for 12 yrs(1987 mustang), before replacing it. Car ran best of 11.54 with E cam, TF heads(homemade port work) and Doug Nash 5spd. We called it "the little motor that could". When we pulled it down, it still looked brand new after 12 yrs of 6200 rpm launches. One season with 347 crank and it was toast and he got a Dart block.
Run what you gotta run. Heck, at least you aren't sticking a SBC in it!!!!
2006/2009 UMTR Points Champion
1964 Galaxie 2dr 390/6-71/4spd
1964 Country Sedan Wagon 428/5spd
1969 F100 428CJ/4spd
1989 F100 302/AOD
1959 B Model Mack