Just to chip in. I am in a similar situation. Love modding and saving old consoles and just started looking at the pile of Xbox's I have and the bigger pile of 1tb hard drives.
I'm currently waiting for the origins image to download as want to add a 2tb to my main Xbox and just found a green ltd edition 'which is what I bought on launch then stupidly sold'
I was going to load it on then get deleting until it was down to 1tb then clone to a 1tb box but not sure if that's a good idea as may be messy leaving unneeded box art etc.
A new image is probably the way to go, like you I'm not especially worried about most emulation as I have 'or will have ' the original consoles but coin-ops is pretty. Also very unlikely to play sports titles.