5.0 Block Question

Hey all! I'm new to this forum, its been awhile since I was an active mustang enthusiast! Due to marriage buying a house (grown up ) well picked up a 90 gt! Back to my roots I suppose. If I could pick someone's brain that would be great. After getting aka Demon home, and yes I will be putting this car through the same hell its putting me thru!! (eventually) mods are minimal at this point gt40p heads explorer intake, e cam, minor etc. Well I noticed after taking the lower intake off I see xxx stamped on the block?? Anybody know what this means? The first day I got it home noticed the flywheel had a big chunk missing so trans is out as well. Also had fuel mixing with the oil, noticed fpr was hooked straight to the vaccum tree. Motor has less than 200 miles on rebuilt engine, tranny has about 25 miles. Any ideals on what's causing fuel to flood engine? Injectors look old,

So you think having the wrong vaccum source hooked to the fpr would cause fuel flooding engine?