Quesion - Santa Maria Style Grill

So, I picked up the steel today to start the grill/rotisserie.
I'm starting with this custom fire ring 48" diameter x 16" high (and yes, it will be sitting at ground level, not on the saw horses).


My basic design will be 24" x 42" grill grate similar to the Engelbrecht Braten Campfire Grill.
http://www.grillsandcookers.com/1000-original-grill.php.

I'll be adding a rotisserie that will sit about 8 inches (16 inch max food diameter) above the cooking grate and it will adjust with the grate.

My question: how tall should I make it; or stated another way, assuming a fire at ground level inside the ring, how much adjustment above the fire should I shoot for? I'm tentatively planning on the 16 inch fire ring depth depth plus 36 inches plus (52 inches) plus room at the top for the adjusting rod, etc (say 8 inches).

PS: to clarify, the SM grill & rotisserie will be a free standing unit, not attached to the fire ring.

Bump

Cabon, thanks. Raising the whole unit is not out of the question if we decide to have a permanent location but that's not the plan right now. I'm more interested in the preferred distance needed to adjust the cooking grate above the coal bed.

Thanks code3rrt. I did use the search tool function and read/looked at some really great builds documented on the site. That's where I got my tentative dimensions roughly ground level to +52 inches should give me 36" to +40" above the fire/coals.