Did you use a mill to shorten down the long guide? did you completely remove the long guide tail that curves on the top of the roof ? i'm going to start on a set of J's for my 427" but will use 2.05 Ferras.
yes, the guide kink was completely removed and the guide itself was narrowed half way to the roof to the pressed in guide.
getting the width between the guide and straight side wall is most important as well, just don't go blind and end up in the head bolt tunnel.
And watch out, each head has 1 head bolt recess that is lower/shorter than the rest so you need to be careful on that one.... but if you want the flow just put a snug fit 'hardened' washer with some putty under it like I did.
