Looking for ssd compatible with samsung r780 any ideas?

It's a SATA HDD with 500 Gb capacity, looks like a standard form-factor 2.5 inch.
If I am correct, I see absolutely no problem in doing the swap. You trade some capacity for great portability and boot time, better battery life. I did this in my Toshiba lappy once.
Just make sure, when all is said and done, to disable the automatic defrag schedule. Defragging an SSD will degrade it's performance.
 


I have a Kingston SSDNow V+200 SVP200S3/240G 2.5" 240GB SATA III Internal Solid State Drive in my R780, which replaced the Samsung 500G HD which crashed. It's been working fine for a couple of years, and certainly speeded things up. Pretty close to your requirements...

John