Boring, rework it to buying time with money, don't replace all science packs.
Idea: Show the dynamic bill value on a "Redeem" button in the top buttons bar.
If you want — research a regular tech, but if you rich — redeem the current one instantly (or redeem up to X % — this is so as not to completely throw away the idea of science packets). Example: You can allow up to 50% (configurable value) of the technology to be redeemed instantly, and the rest to be researched in the usual way.

This is a pretty simple mod as en extension to support other "ideas". I don't know what mods/scenarios you used, because by itself this mod isn't playable without other mods/scenarios.

For more complex/different stuff, I could make another mod.