Three speed to four speed

You already have most of the swap pieces. Check your current bellhousing and see if it is drilled for both transmission patterns. Most of them from '69-'76 were. If it is, all you will need is a non OD tranny, shifter, and front driveshaft yoke from a 727/833. If you want to use an OD 4 speed you can get everything you need from a Volare/Aspen. This would include the bellhousing, clutch fork, transmission, shifter, and front yoke. Good luck with the swap.