what is the differance between 18* and 23* heads? which would be best for an lo5? also what would be the best cc size for vortech heads for the same motor?

and yes I'm well aware that new heads isn't the first thing to to to a motor however I am mostly just curious, also I wasn't sure how to search for this particular topic.

 

18° heads require an 18° valve train. You need heads that are for 23°.

The 350 vortec heads are 64cc.

 

18* heads are race parts only and cost several thousand dollars.

 

This refers to the angle of the valve in relation to the deck surface. Standard small-block chevy angles are 23º. Gen I TFS TW heads have an intake angle of 13º while the exhaust is still at 23º. Not sure about the Gen II heads, don't own 'em.

Incidentally, the TFS 18º heads are about $2K from Summit.