I have a built 403. Runs great. Just not the power I thought it would have. Doesn't spin tires like yours......previous spent about 5k on the rebuild. Has good parts in it but not alot of power. I can post a build sheet to. Did you have to do alot of modifying to install the LS motor?
Please do. My 8 to 1 403 that only ran a 9.7 in the 1/8 spun the tires hard with a no slip locker, whether 3.42 or the stock 2.56 gears.
I think my compression is 9 to 1 or a little more. Stock 3.42 rear end (if it's the original) and stock 200r4 transmission. Shifts pretty hard. Runs good. Just not the beast they told me that it is. 1406 carb.