Serge, my interpretation (and I reiterate, my) of J and K is thus-
If you car is to be 1970 spec then it needs to conform to J of that period, in other words the version with that or a preceding year date. I haven't studied it, but this could be overridden by App K, which is updated regularly rather than a period 'set in stone' document.
Any modified parts fitted to the car now will have to be either homologated at the time or with proof that it / they were used in period. Normally in a competition run under an International permit. Just because something was 'free' in period, it doesn't mean it is 'free' now. This is perhaps why you don't see some models racing nowadays, as they were not homologated or never competed at a high enough level for proof of any mods to be available now.
All this is of course only needed if you want to race the car in events run at FIA level. You could always build (for example) a replica modsports Europa and run it in events that are happy to accept it.......
I may have said this before, but the MSA scrutineers that are responsible for HTP inspections are usually quite happy to give guidance on interpretation of J and K. They are listed in the blue book and on MSA website.
