66 Dart GT HT Whatsitgonnabe?

Not sure about the pushrod relocation idea. You may be able to move them, then clean out the hump. There may not be enough material there to do this. Thats why i think the T/A heads were different castings.

Good score by rhe way. Valve guides on these are a press fit, then the hole for the valve stem is machined for proper stem clearance. I would imagine a good machine shop could fix em up for you. Here in the states our machine shops are used to seeing american and foreign. I think all they really need is the specifications it needs to be, and the parts.

A buddy of mine years ago had a 1981 motoguzzi 1000 SP. Had to get the crank balanced for his new rods, and pistons, also needed a valve job on the heads. A local auto machine shop fixed him right up despite never messing with one of those before. He gave em all the specs in metric, and away they went. Everything came back perfect.
If I can just get my hands on a press, I think I could get the guides out and new ones in. I'd do all 16, I think. I guess the internet knows what diameter the broach needs to be.

I'm not sure push rod relocation is possible on these heads either. It would depend on if there's any water jacket in that area. otherwise, it would just be a matter of removing material where the push rod needs to be and filling up the old hole, either by pressing in a rod or just JB weld. I know Steve Dulcic of Hot Rod Magazine used JB weld to do it on a set of Edelbrock alu heads. He had to move the intake mounting hole, though, which might be additional hassle.

I haven't looked close enough at the heads yet, we'll see whet happens. I'm on a budget, though, so buying time at a machine shop might be difficult. The ones I know of have all expensive CNC equipment only so time in those is expensive.