KB 191's And a 1051 Head

051 heads are open chamber like all the other 360 LA heads. Pistons should work fine, but clearance should be checked and that will help choose a head gasket thickness. Read the KB instructions carefully.

4.88 gears with 26" tires seems like too much gear, especially for 1/4 mile. 4.56 would still be zinging it. 360 has a long stroke, so use the torque. X or J heads might be a little better, but the quality of the valve job and valve design would make more difference.

Hopefully you have frame connectors and can add 2 more bars to make the roll bar an 8 point. The extra bars would connect the frame connectors to the side of the main hoop behind the seats.

If the heads are done, the springs may dictate what cams you can choose from.