I have a set of gt40s off of a 94 cobra with 10000 mi on them. I also have a set of gt40p's with 140000 mi. Should I use the 40s or give the p's a valve job and use them? Using mac long tubes so headers are not an issue. I will be running the 2031 cam and the explorer intake. moneys pretty tight so building this motor on the cheap. I will be using the stock cobra short block with 10000 miles on it.