With a 96.2 Feedback Rating I wouldn't buy a bag of rubber bands from them, especially trusting them to ship to U.K. My suggestion is to take some time to mike out the engine: rods, mains, cylinder bores, heads surface, valve guides etc. and see where you're at and exactly what you'll need.
Finger-tight mock up all the parts you can, seeing which bolts you have and which fit where, and of course clean bolts first. Special markings on bolt heads give a hint but all Mopar bolts are at least Grade 5. If you're short some bolts contact former owner, doubt he'd toss them. Always good to run a tap down the bolt holes when prepping.
Also check the transmission to insure it's a big block 727, not a small block 727 or a 904.
May be cheaper and easier overall to locate a used running engine for now. You need different motor mounts for a big block than for car's original small block. Shuemacher has fine quality changeover mounts, excellent reputation here.
http://www.engine-swaps.com/For gaskets the finest are Fel-Pro, quality/fit far above the others, about the same price.
These 2 things of transmission type and existing motor mounts may be part of why the vehicle never got re-assembled, "Oh, right, guess I forgot to mention that...".
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