Have Someone already done that?The only thing you have to do is pull out the 318 E.M and put the 340 E.M isn't it?What's the diference between them?more exaust capacity?
It seems as thow a couple people have done this.The 340 manifolds has bigger ports than the tiny 318,and flows much better.In reality the 318 can only flow as much as the tiny 318 heads will allow,but these with the dual exhaust should un-cork it a bit.If I ever go to a 340/360 the exhaust will be done.
Installation is the same,just use a 340 exh gasket !!!!