ok.. gotta clear up some misconceptions...
a/g body stick shifts were in 78 malibus, as i've got one! they were also in elky's, monte's, and cutlass', however the cutlass got the 5 speed. i'm unsure what they use for a bellhousing. malibu's, wagons, elkys, had the stick shift until 81 model year. V6's came with 3 speed, V8's came with 4 speed saginaw. all V8's in bu's, and wagons were 305's only, however the elky had a 350 4 speed combo.
what you need. lakewood bellhousing would be better, with F body clutch fork, factory G body Z bar, and pedel setup. the bars and pedels are for sale all over the place. Kiesler no longer sells the kit, or any of the parts to my knowledge.
if you decide to go with GM parts, try elcaminostore.com online and they were selling the parts. look for a GM bellhousing that ends in numerical order "606" (last 3 numbers on bellhousing). This is a rare piece and will cost you some $$ You can go with another GM bellhousing (11"), but will cause complications with the clutchfork as the angle will be wrong. The factory clutch fork is curved to meet with the rod, and is no longer produced by GM. You'll also need the frame bracket that bolts in the inner fenderwell drivers side. you'll see 3 holes there towards the rear, those are where 3 self tapping bolts go for the bracket. you'll also need the ball. The factory clutch setup is a 10.5" setup, and will handle most V8 combos if you use the right clutch. I've had good luck with Hays, and centerforce. also, go with the roller input shaft bearing instead of the brass bushing.
If you stick with saginaw 4 speed, the Th350 crossmember is the same, as is driveshaft, and speedo connection will hook right up too.
the problem child is your neutral saftey switch. factory standards have a different setup so the car will only start when clutch is depressed. also, the reverse lights won't work unless you swivel your column for backup lights. best to look around for factory stick shift column.. it will also have the key release lever under the ignition cylinder. hope this info helps..
Mike