Yes a tunnel ram will work well , with some changes. The 305 heads,,, what is the casting number?
305 heads need max porting to benefit from the big valves. Are they max ported? If not , get busy with the die grinder. You need max home hand porting to wake up the 305 heads.
The 4416's are the best of the bunch.
The tunnel ram likes lots of cam (a solid is highly recomended) a big converter (3500+++stall) and big gears.
cams: Isky 201027 (at minimum) 201534 201CC1 are all good
Isky 235D springs.
650x2 750x2 carbs ( edelbrock or holley DP) on the T ram
Get the true cr up to 10.50:1 Deck clearance, chamber volume, gasket choice.
Ditch the gear drive.. Sell it to a poser. It is slowing you down.
The cam you got now needs a 3500+ stall ...All the Isky solids listed are way better.
More gear is more better.
If your 305 heads don;t look like this, get busy with the die grinder