[ponyakr]

today, if i had 2 start from scratch & build a street/mild bracket 455, i would not go hi comp. there are lots of advantages 2 runnin less comp. 1st, you can get by with pump gas or a mixture with just a small % racin gas in the mix--so the fuel is cheaper. another advantage is less chance of head gasket failure. also these heads are much more common & therefore cheaper. they were used in various forms from '71 thru '79. the most common & popular today is probably the 6x--used on 350's & 400's from about '75 thru '79. they already have the large intake valves, screw-in studs, & all 6 holes for header bolts. they are readily available from cheap, bare, rusty 2 all out, ported big boy sets for nearly $2000. this is 1 area where i have a different opinion than the 1 held by most on this site. most seem 2 think that the iron heads are almost useless unless they have at least a mild port job. i never used more than a mild gasket match clean-up--not even that much on most--& we ran as low as 12.40's with a stock 13" convertor, q-jet, & 3.55 gears. those same motors with a little stall & 4.11 or 4.56 gears would easily run hi 11's in a '68 bird like we ran. so how quick do you wanna go? or, if you have a street only car, a non-ported head 455 will produce all the tire melting torque you could ever need. but if you know how & have the time--knock ya self out--port it. just know that you won't notice much difference in low end torque, nor any huge reduction in et. 2 me(just my opinion) its just not worth the effort--once again thats for street/mild bracket. i do have enuff sense 2 know that a properly ported head will flow more air & make more power than a non-ported 1--but my gbt is "as cast".