I've come across a GX engine for sale, just need to know a little bit about the specs and what it's worth?

Specs are here: Tech Section: Datsun A12GX Engine

if its a gx and the heads not completely rooted or full of corrosion don't worry about the specs just buy it. if its in reasonable nik and the owner's not sure offer a few hundred and see what happens
is it a 1200 or 1400 ??

It's a 1200. The engine is seized due to water in the cylinder (it was being 'cleaned' and someone decided to crank her over without checking). It is completely original however and I would have rebuilt it before transplanting it in my beast regardless of condition.

if its been turned over while the cylinders are full of water ??? (who cleans the inside of an engine with water ??) fare chance the cylinder walls won't be in good shape
i'd pull the head off if you can and check it for any major corrosion then, if it looks ok - most can be fixed up anyhow, chack the bores for any rust rings, and if possible whether they're straight or slightly distorted. offer $100 bucks for the lot get a new block and transplant the whole lot iito it

Yeah, the cleaning bit got me, the dude who has it now didn't do it. Water won't clean much off the inside of a cylinder.

Is it a complete genuine 1200 GX engine, or is it a later A12 GX from a B210 [120Y]? By complete, i mean menifolds, carbs, heat shield, air filter assembly, fuel pump etc.

If it is a genuine & complete 1200 [1970 to '73] engine, then it could be worth quite a reasonable sum, even in a sad condition. Any bore damage can be fixed with a rebore, & GX pistons were the same as all other 1200 ones, so replacements are no real problem. The cylinder head corrosion [if any], can be welded & repaired, & the the head generally can be saved with anything from a minor top overhaul to a major recondition, depending on condition.
Feral saved mine this way & i'm delighted with it.

A freshly reconditioned, but otherwise stock 1200 GX is a true delight to drive. Subtly improved ones are even better.

The only diferences between a stock 1200 short block assembly & a 1200 GX one are the camshaft & the water inlet pipe at the front of the block.

If it is truly a genuine 1200 GX engine, then get it. If you don't want it, then please drop me a line with contact details, hell, i won't let it go to waste.

I finally got a price on the motor. He's after $500, what do y'all think?