I dont think a 240/300 will bolt in your falcon and it definately wont bolt to your original trans as I think it has a different bolt pattern,the 240/300 sixes might be a little longer and might not fit in the engine compartment without a bunch of work, If you want a little bigger six a 250 from a maverick should bolt in but you would need the trans that came with it as I heard the 250 has the same bolt pattern as the 6 bolt smallblocks,it would be easier to find a 302 and C-4 to drop in it and I would not worry about the driveshaft as one could be found at a junkyard that should work or a driveshaft shop will be able to make one easily. Jeff