Dont bother with the re-drilled heads, just do it right and get the proper intake. When I did my vortecs I got the heads off ebay new with chrome centerbolt valve covers($45 through summit) for $450 shipped to my door. I got my edelbrock performer intake + gaskets from summit for $170+20 and my valve cover gaskets for $9. I got .041" head gaskets and head bolts from the chevy dealer for around $60. Looking back, I could have used thinner head gaskets for more compression and still be OK. I do run 91 octane now just because I like it more, I could probably get by on 89 or even 87 if I didnt mind dieseling when I trun my truck off. All in all it wasnt too difficult to do, the hardest part was adjusting the valves but that isnt anything that cant be done quickly with a little practice. Overall a great thing to do to your truck.