hi mike, i have an original General Arrangement drawing for the GNR atlantics from BR signed by J.F. Harrison himself. if you are interested, send me a PM.
the variations from martin evan's SOUTHERN BELLE and say LBSC's MAISEE in 3.5"g are pretty minor and mainly deal with the shape of the chimney and safety valve cover and the slightly longer frames at the rear and cab and the shape of the tender on the LBSCR H2 Atlantics. in fullsize the differences were more marked, and those of us who are 'Brighton' fans reckon the H2 LBSCR versions were far superior to the GNR Atlantics!