i used the 250 i6 stands in the same place for my 305
but i had smaller valve covers and plenty of clearance and didn't want to have to change driveshaft length and gearbox crossmember mounts.
plus i plan to go back to i6 .
you may have distributor issues as well if you use anything other then a standard one.
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1969 stepside-305/4spd/12 bolt posi
http://67-72chevytrucks.com/vboard/s...d.php?t=477157
1968 pontiac lemans convertible-350/pwrglde/10 bolt
1934 oldsmobile sedan-350/350/12 bolt posi
1930 model a pickup-350/350/jag ind
1928 model a roadster-283/350/9"