well i guess im the resident 283 guy to go to here. <or so im told > 300-375? no problem. id say bore it .60 over get some HO 305 heads<be careful not to run to bad boy of a piston compression is easy witht hese heads run flat tops u can have 10-1, or some mildly chambered heads say 72 cc or so.<considering i run 64 cc heads with 12:-5-1 domes in my 283>smak those on there. get a 270-h comp cams hydr. and a 600 carb and you should be able to sneak out 300+ easy as pie. or you can bore it .80 <or up to .125> and add a 280-h comp cams <best street cam for a 283 i sware> and they have a very nice lopey idle. i ran a .125 with 11:1's and a 280-h cam with a 600 holley <well it was in the nova for about 8-9 years> and it got at least 12-15 mpg. if you kept it .60 with the mild heads, some dish or flat-top pistons and a nice mild cam you can get 20-25 mpg and still have 300 horse's not hard to do! if you need any more advice email or pm-me. AND YES the easiest thing to do to a 283 is overcam!