Hi xhall,
I understand where you are coming from as far as the amount of bits and pieces required to get this machine back into some sort of serviceable order, but as I have plenty of these in far worse condition then I could get this machine up and going in no time into a well running machine. I must admit I'm a tad perplexed at how you come to the conclusion that the engine is not the original. Personally I would hoik the donk back to the tip and find a suitable replacement, but for Corduroy before going any further I would check out the state of the rails and see if they are cracked, if they are then I'd use this one as a parts donor and bin the rest. Consider this xhall, at $30 you try and find any parts for these machines under that figure. If you only salvaged the reel and a few sprockets you've got your monies worth. Have you priced a bearing carrier lately ?
I'd like to see some photos of the drive train with the chain case removed.
Honestly I know it doesn't look good but sometimes after all the gunk is stripped off you might find a salvageable machine underneath.
Cheers,
BB