I cannot say for sure, but I doubt it.
The fact that EFI partition is present indicates it must have been installed using EFI boot drive set first in BIOS Boot order which means that it will probably need to have that set first again to boot, from what I've seen with EFI BIOS.
I doubt that would work if you recover the System boot files into Win7 partition or convert the 100mb to System partition. However if you do this then later setting the HD first to boot might work. You'd also need to do that now to mark Active and run Repairs to recover System boot files into Win7 partition, or delete and recreate the 100mb as Active System partition.
It would be experimental, but at worst you'd have to reinstall Win7 and then could look at options to avoid EFI in the future - normally by choosing the HD to boot first in BIOS and not EFI Boot drive. Some BIOS have other settings to change this.