Welder,
I too am building my first oven, but mine will be gas.
This link
http://www.coatings.de/manual/kap11-1.pdf
should help in determining the BTU's required to get your oven up to temp. Then use table 11-5 to figure out what size heaters to put in it. Nix all the formulas about chain weight, conv. speed and all that other stuff since this is not a conveyor and go straight for lbs/hr. because you will need more BTU's to heat the parts too. I think that should get you real close.
I will use a small squirrel cage motor on mine. I don't know, but I think if you were to circulate the air a few times per minute that it would keep the temps pretty consistent. I took a motor from an old food service convection oven at work and it is way too much air... I it would blow the dust right off the parts. Since you are going to install a convection fan in the unit I would put the heaters in the bottom of the oven to avoid any extra radiant heat from parts being to close to the elements.
Bill