It isn't exatly the same as the other engines. The engine in questions has SVO GT40 alum heads and valvetrain and is just a 302 botton end. The 345 HP is at the flywheel not the tires.
With a gear swap your speedo should be off on a progressive rate. Meaning it should be off a mile or two down low and the difference should get larger the faster you go. By putting in your 200 mph speedo you are just going to throw it off more. You are going to need to get your gear, whenever...
Personally I would mix the 2. You can do the Ac elim and the cam and gasket change. You probable can skip the radiator unless you are already having overheating problems. that will free up the money in option to include most of option 2 at the same time.
I forget which autoparts place it was(or mail order) But they showed 2 different ones from the factory but the aftermarket ones were the same number for both of them.
Sounds like it is the middle t handle thing. In don't know the actual name of it but it connects the handle to the 2 rear cables. 50 resto has them for $23 or something like that. I just ordered one myself.
If you have the money to get it from where it is now to where you want it to be and still come up with a price that you think is decent then go for it. I personally would walk away from the car and find something else that is a little better for a little more money.
There is no way I would pay that much for a car, in what sounds like bad shape. I only paid $2500 for my notch with a 2 year old paint job and 111k miles.
Is there a chance that the quads had already been flipped before? Either way I would take them off and live through the traction issues until you can get a set of control arms. It is better then needing new tires sooner.