I have a 59a in my 33.
here's what I did
Used those horse shoe bits on the front engine mount, plus a small space ,I think 1/2 inch.
used a turned down twin pulley,( cut the outer one off)
turned down the crankshaft pulley bolt ,( turned the crank start dogs off)
cut the front of the scatt crankshaft off to suit single pulley
used my stock 33 manifold, carb and generator.and fuel pump
used the 59a water pumps.
Used my stock 33 distributor ,But fitted an 11A advance.
used the hose kit from B/drakes.
Used the stock 33 exhaust manifolds
Nothing else needed changing
It has been in for years,
Lawrie