Best of luck. I love projects which challenge the norm and force you to think out of the box.
A couple of practical problems you're going to face.
Unless your project car is built around an existing chassis, getting it registered is going to be quite a problem. Our excise and taxation wallahs are going to question you at every turn. So, unless you've given some serious thought to this aspect, a tubular chassis is going to be a bit of a problem. You can build it, but you won't be able to drive it on the roads.
There are merits and demerits to all the layouts (FR, MR and RR). If you truly intend to keep this cheap and economical, you may want to go with the most conveniently available, rather than the most aurally appealing.
Custom fabrication, even in Pakistan...is very expensive. If you think you can fabricate a one-off diff that is reliable, sturdy and efficient...and do it cheaply...well, you're living on a different planet, brother.
4AGZE engines (the supercharged ones from the MR2 T Top) are somewhat rare, but not completely so. The're slightly expensive, but not inordinately so. In comparison, 4AGE engines are fairly common, fairly cheap, and offer great performance and economy. Some of them come with LSD gearboxes, which would suit such a project.
Someone mentioned using a Beetle frame. I personally think it's a terrific idea. You have an existing (registered chassis), you can mount the engine at the rear, bung a radiator up front, craft your tubular skeleton around it, have all the necessary suspension pre-sorted, and devote time and effort on performance rather than fabrication and design. Personally, if I were to ever go down this path...this would be the route I'd follow.
Like I said earlier...I love such projects, and the creativity, passion, and radical thinking they engender. All the very best of luck with your thoughts. Hope to see your project car blazing trails on the roads, soon!
