Hydraulic lifters in 351w

You don't need to turn the block upside down to drill the spider holes. Lay the pider in place, and mark the hole locations. It woud be best to have the dogbones and lifters in place as well when you do this. Drill a hole about .5" deep. I think this is how deep I drilled mine but I am not sure. This allowed enough thread, but did not break through the web. Also, check that the dogbones will seat correctly. They should sit flat on the block, if not you will need to break out the grinder so that they will. If the motor is already assembled you will have to take great care to contain all metal shavings, and clean the valley when you are done.
Unless you are running very high lift and/or very aggressive ramp rates, the stock lifters should be ok. What cam are you using?

BE careful... guess where those bolt holes go?? Yep!! right into the cam journal!! Might want to make sure that doesnt happen!!.. Or drill and tap and then have New cam bearings put in IF you bust thru!! There are a ton of good flattappet hydrolic cams out there and will build a lot of power and you sure as helll dont pay 400.00 for the cam and set up?? Just a thought!! either way be carefull!! cool??

Just me...........................

Thumper

They are pricey, but well worth the money. You are not limited to running reduced base circle cams, not tie bars, and no stock lifters. They drop right in. Mine saw 6800rpms on the dyno several times w/no float. I would run them again without hesitation, believe me I was not happy to spend $410 on lifters, but at my machinists and assemblers recomendation I was glad I did.
Mike.