A few questions about free 9400f and 3070ti

So was given a old I buy Power PC with a intel 9400f, 16gb Ram, and a GTX1650 Super. It has a Asus Tuf 550w power supply

I already have an old 3070Ti 8gb thats sitting in my closet. And was going to put that in before I saw the PSU wont handle it.

My goal is a budget gaming PC for my little brother.

I saw some CPU+Mobo and Ram combos on NewEgg and Amazon for 260$ That had a AMD 5500, 16gb DDR4 and A Asus B550 mono.

I would have to buy a windows copy for the new mobo and CPU.

should I do all that, or just buy a 700-750W PSU and throw the 3070 in the PC with the 9400F?​