Well, thanks for all the advice guys! I've pm'd baldy and I'm considering his offer.
A quick decoke on some heads (in good condition) seems to be a better option than chewing-on finding/ordering/waiting for parts and, depending on how much I was prepared to spend, having an engineer install valve guides and the like...
As veesix75 quite rightly points out "...where do you stop"! I know for a fact that if left to my own devices, I would have gone for a full set of valves, guides and cam buckets, maybe even valve seats if I could have got them...because that's what I'm like. The 105 bhp heads does seem to be the most sensible and financially prudent option.
Much of my lavishness comes from being an apprentice mechanic (many years ago) when a full engine rebuild was do-able...especially as I was usually spending someone elses money!
I would be chuffed to do a full engine rebuild on this motor, the thing is, I now have/will soon have enough bits to be able to do one if/as and when the need arises.
veesix75: Was considering having a bit of work done on the standard flywheel. As the frame/chassis will come in at well under 100kg I figured that responsiveness would be more beneficial than torque... thoughts?
Also, although I havn't completely made up my mind, I will most likely be using 15" wheels with a very high profile tyre for the rears (think buggy/baja). This will lower the gearing...right? What are your thoughts on the gearing given the trike will be lighter than a standard 'sud, I have a standard 1500 Ti box.