PJ
Your post prompted me to finally sign up to WT after looking in from the outside for some time. I have been collecting information on and off for years for a model of Beyer Peacock 2980 of 1888, a 5'3" gauge 0-4-0st purchased by the Hoffman Patent Steam Brick Company Ltd in Melbourne. It was a near clone of 1827, although with a 7' wheelbase which I think is a bit longer than 1827. BP 2980 was sold to South Australia around 1900 and lasted until 1930.
Before finding the MOSI drawing collection, while in UK for a friends wedding, I went to visit 1827 at the Foxfield Railway only to be told by the friendly midweek volunteers that it was away working at Shildon so a slight detour found it in the goods shed at Shildon and permission obtained to measure and photograph its details. It is much easier to build a convincing model if you have the chance to see the real thing up close. MOSI don't seem to have a drawing for 2980 so I found the closest possible match and used it as the basis for a drawing (still only outline to work out how it all fits together).
Apart from the wheelbase, the differences between 1827 and 2980 are remarkably few, basically being limited to the wheel centres, the width of the footplate and cab to accommodate the extra 6 1/2 inches in gauge, and the shape of the smokebox sides, again to suit the wider frame spacing. The pattern of the characteristic BP snap head rivets seem to match almost exactly. I am not sure how the order (7076) for 2980 came about but it seems the BP drawing office didn't look far for inspiration and there was no apparent product development in the ten years between the locos.
By coincidence, I finally started making parts for the loco last Saturday using it as a trial for milling wheel centres with a pantograph milling machine. Successfully, but they are still a work in progress to finish them off. The model will be 1:48 scale on 33.34mm gauge with exact scale tyres, so a bit smaller than Scale7 on slightly wider track.
It will be interesting to watch your project develop.
Fraser