Everything you list can be moved to a 'new' bike should you find the 800 not speedy enough for you so no real waste, money-wise. Ma had one and it's not a bad bike, really. Sure, it's not particularly fast and it's a bit heavy but it rolled ok. The original components are still on it and still working alright. The only thing wrong with it right now is a bent rim (you can't hit curbs, apparently) and dry-rotted tires that need replacing. My sister rode it relentlessly for awhile and now my cousin has it since the sis upgraded. Can you take yours for a few trial spins to work before you begin construction?
My '91 Trek 830 made a fine commuter.