no diff in 862 and 706s flow the same
706s milled 30 thou is about 10to1
can be milled up to 50thou

 

As others have already said the only difference between the heads is the intake runner size and the intake valve size. Therefore IMO if you plan on doing ANY other modifications to the motor (larger cam, fi, n2o, etc) you are ahead by starting with a set of 243's. If what you have stated is all the modifications you will ever do to that motor then stick with the 706's.

 

I've got a set of milled 243's that I'm going to throw on my truck when I do my cam swap along with everything else. If I get mine done before you do I'll let you know what happens

 

im looking to throw on the 243s as well..probably milled .35 using stock replacement gaskets
im guessing ill see around 20rwhp