It's a shame that Clever Forgery isn't making their helmets anymore...they were by far the finest out there, I have one and am lucky to have it....agreed with what has been said, Steve Kiddle's helmets at Pegasus Militaria are the best out there at this time...and almost as good as what Clever Forgery was making (minor details gave CF the edge).
Warther has a nasty reputation for a reason...they are absolute crap, the workmanship is so poor I'm suprised the seller can do so in good faith and should be avoided like the plague.
Unfortunately I don't know of anyone doing a good reproduction liner only conversion of the helmet. His best bet is to contact Kiddle to see if he'll sell him a liner and chinstrap only, or possibly buy a complete helmet. Kiddle's Pegasus Militaria stuff is sold by Jerry Lee at
www.whatpriceglory.com, so he'll save on shipping etc. by doing so...
My two cents...
Tim