no solder paste needed just flux there is enough left on chips from old board
And it is doable with a heat gun i have use that and my ir rework both work fine just need to be careful with heat gun not to blow surrounding caps away
This would make a neat DIY project. I plan to order the boards and give it a go. Any additional last minute advice. And like I said its been a very very long time I've don't any kind of soldering.
This does sound like the best option. Let us know how it goes!
Keep some extra flux around, and be patient. It can take a little time for this style of chip to loosen up, expicially if they were made RHoS compliant (the solder for that requires more heat, and releases a little less smoothly.)