if i were you i would build the 340... its going to be cheeper and more parts avilable.. . you will be able to run a better (more dir and lift) cam ..better manifold.i think you said you also have a pair of j heads ,if so you could realy make some hp..use the 273 rockers .i use them on my race 360 moter no problems . the 904 will be ok..the only problems are no aftermarket shifter for the two cables...and the torque conveter will be trouble,because they used a smaller size input shaft..up to 66 ...Rick at
A@Atrans can help you with that ...i run a 64 904 trans in my 64 360 dart race car.. using 64 65 consol floor shifter.a late model in put /reacter asysm a with 5 clutch front drum and 5clutch rear drum all from
A@A NO PROBLEMS a 4200 stall convertor from dynamic...12.3 ALL DAY A1.69 60FT
A@A number 317 831 3066 dynamic number 877 846 5876 good luck