To answer your question: both kinds of VPN setup can communicate with each other kind. Troubleshooting is much easier with Interface mode though, so I'd recommend you re-create the 4.3 VPN in Interface Mode. When creating phase1, there is a checkbox on top for this. You can only change the setting until you hit OK for the first time.
Make sure your Quick Mode selectors are correct on both sides, preferably not wildcards (0.0.0.0/0) but even that would work...
If it doesn't work right away please post the config (text form, from CLI) and then we can further debug the connection setup.
"Kernel panic: Aiee, killing interrupt handler!"