Jeff,
I welded my own tank together and included some threaded ports in the bottom to allow me to install a colant heated fuel pickup and tank heaters. I was also able to install a 220vac water heater elemens (run at 110vac sicne vegoil cannot absorb heat as well as water) for pre heating the wvo in very cold MN winter.
Don't forget baffles.
You may get some good info from my website:
http://danalinscott.netfirms.com/
It has a huge FAQ page as well as design files for sale which simple to assemble (from mostly off the shelf bits) vegoil conversion components and prefilter units. These are not free but should save you several times their cost.
And please feel free to contact me if you have any questions about prefitering wvo or using it as fuel. I have converted quite a few vehicles, gensets, and tractors.
The cost of fabricating your own conversion "kit" is usually 1/2 to 1/4 the cost of purchasing one ready to install. And the key to happy motoring on wvo is having a good prefiltering unit. The simplest one I have desinged and used costs less than $100 to make and easily fits in a 3'x3' garge corner. It incorporates its own resevior for filtered wvo and a simple pump so you can fill up directly out of it.
Over 30,000 miles on wvo so far and o major problems.
Dana