One computer into two

[TheRealAlpha2]

I have an old refurbished HP elitedesk 800 g1 sff that I bought as my first desktop about 3-4 years ago, still going well. Plays most of the games I want it to, I've upgraded ram to 32 gb (8x4 dual channel), added a GPU (upgraded from a gt1030 to a gtx 1650) and then upgraded the processor as far as it would go for the sake of peace of mind (from a i5 4670 to a used I7 4790k) and have several hardrives installed... more than the computer was intend to have.

During my CPU upgrade I realize I have all this stuff jammed pretty tightly into a SFF case, but what if I got a Mini tower off ebay for cheap and moved the processor, Ram, GPU and drives into one for more space/airflow (granted this computer doesn't seem to be over heating right now, but I feel like the potential is there if I start gaming and streaming. If I did get a Minitower it'd be easier than trying to coax all this proprietary HP stuff into a new "full size" tower and figure out cable management. I could then take the old Processor put it back into the SFF with the old 8gb of ram (4+4gb dual channel) and the old 1030 GPU with a cheap harddrive and effectively have a second PC. This way I'd have a second PC that can do the actual streaming to allow the main computer to have all it's power for games or whatever else I do.

Before I do it I'm just wondering if there's anything that would keep this from working, I've seen "Bare bones" Minitower cases on Ebay, with a motherboard PSU and heatsink but no CPU or ram for maybe 40 bucks (although shipping is practically as much as the case itself). I sometimes see G2 case's cheaper but I'm pretty sure it has a different motherboard (lga1151?) so that version is out of the question, but a G1 minitower? (I suppose I could also just buy another sff G1 case and move some drives over to accomplish a similar thing, but I'd prefer to only have one main PC with a smaller secondary, and not have to swap between two for the same purposes.) Any thoughts on the feasibility of this?