What condenser lenses for LF enlarger?

[scratched&grainy]

Hi there,
Now I'm sure what I'm about to ask is somewhere on APUG but I haven't found it yet hence the new thread. My question is:what condenser lenses do I need to make a print from a 7x7 inch negative? I have a devere 507 enlarger which i had machined out to accommodate 7x7 glass collodion negs. Unfortunately the condenser lenses do not cover 7x7. So I was thinking of buying some durst condensers which are in square frames and making a box for them and mounting it between the light source and the neg carrier, but which ones?
On another note -my camera is about 9x9 inches so i was also thinking of making an enlarger for bigger negs, so i suppose condenser lenses that cover 10x10 would be needed for this? But which ones?
Thanks
Mark

 

[ic-racer]

Is this the same question here or anything new to add? (there was a url link here which no longer exists)

 

[Rick A]

I have a 5x7 Elwood enlarger, it's a diffusion type, I would suggest you use yours the same.

 

[scratched&grainy]

Same question. Still trying to solve it.