Gradually changing tempos

Hi,

I’ve been asked to splice two songs together for a first dance at a friends wedding.

They’re the same song, in the same key, but one is the acoustic version (single guitar and vox), the second is the full band electric version.

I can easily fade in the full band version and simultaneously fade out the acoustic version, but the problem is the acoustic version is at a slightly slower tempo.

I’m thinking of using rubber band to amend the tempos over the fade in (not a function I’ve used before, but I’ll have a play).

Is there any other plugin capable of doing this?

Many thanks!