Oops. Ed you are right, apparently the aircraft at Riga was the Ju.90 V7 (a photo clearly shows the code J4-CH). Peter Stahl in his book "KG200 the true story" ( he served in it) calls it 290A-0. Green said the 290A-0 was W/N 0150 but note the Junkers listings. Must admit I get confused sometimes by these prototype / pre-production etc. designations.
This is the link.
http://hugojunkers.bplaced.net/junke...tion-list.html
Regards
Nick