the Toyota engines are just too good to pass up. $ for $ best engines to do a budget build. if u can build an 8-sec car for $10k or an 11-sec car for $10k i know which option i'd take
the most economical and cheapest way is to buy someone else's hard work and hard earned spent money. i have seen unfinished projects that people have spent $20k+ on sell for $5k. go over it and make sure all is good before you buy it. no point starting from scratch if u dont need to. the money should go into the chassis, that is the most important part. no point building an engine if the chassis is not setup right, your shooting yourself in the foot before you even get started. the car on my105 has run low 9's almost 8's and he only wants $4k for it, that in my eyes is a bargain and a half. if the engine is showing power to run 9's and ur running 11's because the car isn't setup properly, what's the point? you want a good consistent car.
you can pick up good reliable strong boxes for around $2k. Neal Trans in the US can get a 1000hp powerglide delivered to your door for under $2k. get the right person to build you a box and it will last a while.