Hi from UK.Help wanted.

[Generallee]

Hi everyone.I live in the UK and have bought a 55 SWB stepside to restore.
It is a bit of a bitsa (bits of this, bits of that!). It had no engine or box, but I came across what I think is an early Chevy V8 and 2 speed Hydramatic box.
I have fitted them in the truck, but can't find any information on the engine with the numbers I have.The gearbox is easy, it says CA-56, 5899 - so I would be right in thinking this is a very early 56 gearbox????
The engine has a number stamped on the side, just above the sump
A34715028, and what looks like 523283 as the casting number.
Anyone help me out with age/size of the engine????
Not many people know much about these trucks over here.
Any help appreciated!!
Thanks
Tim
ps. I luv american cars/trucks and spend alot of my time rescueing/restoring them.