Actually, simply shortening the pilot and cutting the master mechanic smokebox extension off isn’t particularly difficult at all. - Neither is taking about an inch or a bit more out of the middle of the tender.
Moving the cylinders back to turn it into a 2-6-0 can be done in an evening (you’d also need to shorten the part of the boiler between the stack an the waist transition by an equal amount, or remove the section where the generator sits). As can moving the cab forward or shortening it, and then shortening the rear overhang and firebox… I’d guess you could remove about 4" on that locomotive superstructure without too much trouble… And about the same on the chassis. You’d just have to move things around to make everything line up.
Yes, the end result would be sort of puppyish in it’s proportions, but is that really a bad thing on a Christmas layout? And it’s a cheap alternative, even if you had to buy a used surgery candidate… and/or a Delton c-16 shell and cab if you really make a hash of it. (We’re talking anywhere from $0 to $100 vs + $300 here… not chump change, especially if you enjoy butchering on plastic anyway - perhaps enough to finance almost everything else on his holiday layout)
Yes, he could always BUY, but he said he was looking for alternatives… Would you tell a guy looking to fix up his Ford to buy a Cadillac? Yes, the Aristo 0-4-0 is an option, and actually a quite good suggestion - IF he needs to buy a starting point locomotive anyway. Hartland may be great stuff, it’s just a bit spendy.