Hey Brent,
I will give you method I used many times with people and never failed me, seems to work really well. Obviously, you need to make sure to match everything to right interfaces on the new appliances.
Streps I use:
1) Get show config from existing firewalls (file name can be anything)...from expert mode -> clish -c "show configuration" > /var/log/hostname-date.txt
2) Once you get them off the boxes, go through the config and compare with interfaces on the new firewalls
3) Go through 1st time wizard on new devices, apply eval licences (for the time being)
4) upgrade management server to R82.10 (if possible, or have it at least on R82 latest jumbo)
5) copy bits and pieces from existing show config files to the clish of new firewalls, just make sure to map proper interfaces, so you can do file compare later
6) do NOT do load config from clish, as that would load config even if its wrong, though would error out, unless you did set clienv on-failure continue, which I do not recomment
7) Once you verify the config, you are ready for the cutover
8) use below post to do this when time comes
https://community.checkpoint.com/t5/Security-Gateways/Replace-Upgrade-Cluster/td-p/69216
9) MAKE SURE that sync interface speed/duplex match, as thats super important for clustering to come up
10) Be proud of GREAT job you did! 🙂
Hope that helps.
Be free to send me a DM if you need further clarification or reply here, either way.
Best,
Andy