[b-man]

The only reason to go 11-bolt is if you can’t source the one year only 1968 cover (8-bolt pump/late balancer).

There’s no discernible difference between 8 and 11-bolt pump cooling capabilities. A friend who’s built numerous engines for himself and many others even found his coolest running engine had the 8-bolt pump.

Of course there are numerous factors affecting how well an engine cools in any particular car but for the sake of originality and ease of accessory parts compatibility I’d be trying to source the correct 1968 cover.

The 11-bolt pump is not the magic bullet, running hotter during the summer with the A/C running is to be expected. Maybe a radiator or fan clutch replacement or upgrade would be worth looking into.