I ran 8-10.5 on my 14.5 x 32's on my 3200# 65 442 clone running as quick as 9.90.
If you think you're 60's are inconsistent , try radial slicks! On a poorly prepped track my 30 x10.5 radials will 60' Either 1.50 or 1.80 ,& not much in between. Now on a decent track they'll be 1.50 all day!