Will a type r Intake manifold fit on a ls head without modifications?

 

no.

 

LS flows just fine, you can get in there and do a bit of match porting or an illegal NASCAR trick called acid porting, if you know a good welder you can take the R manifold and cut it at the flange and weld your LS flange, there is a lot of work but I wasted time and made one 2 years ago, total waste of time, best to just cut the plenum off the LS and weld on a rectangular tube of like 4 x 4" x manifold length, cut the bottom out and glue it alltogether again.

 

How to convert

 

that was a cool web page art.. They actually layed it out in terms that any idiot like me could understand