Part needed for injection pump

I'm rebuilding the shepherdess's Faithful Transit and need the rubber boot that protects the advance piston on the side of the pump.
French diesel specialist says part no longer available.

Lucas CAV
Type:- 671
Dps:- 8520A480A
Ser:- 20253MGG

It seems to be the same part on most old transits but as it is between the pump and the block, with the inlet manifold over it,the pump has to come off to get it.
None of the scrappies will sell it separately, it's buy the pump or nowt even though they throw them out.
Scrappies run a price fixing thing over here. ie 1990 Transit engine 1200 euros pump 200 euros.
No point using the old cover as it is split and fixing the advance piston if dirt gets in is 200 euros for the 4 little parts as I had to do that on the other transit she bought cheap ( smashed R/H front suspension ) to use till her minion has fixed the first one.
Any one able to help.

Got one 13 euros ouch for a little rubber potty

parts got

so locked at posters request