For sure. All options have their own difficulties, pros and cons.
It's easy to over capitalise in the engine side of things, not so much with costs, but time and complexity.
I think at least the M54 path is cost effective, offering an engine you can read with OBD2 systems for full code support if it plays up which is a real benefit over the older engines.
I've had a few E34s over the years, would like another for sure. But one thing not to forget about is overhauling the suspension, especially on higher km examples, aside from the basics like shocks, its the ball joints, and just about every bush would need replacing, worth it in the long run of course!