According to this (How to spend the Niners $33.8 million in cap space - Inside the 49ers
), the 49ers have $33.8 million in cap space.
They already have a very good running game and the best defense in the NFL. They also have a tremendous tight end in Vernon Davis. They made the NFC Championship Game this past season with Alex Smith at QB.
What they don't have is a big-time QB or a big-time WR. They have enough money to get both this offseason.
(1) Sign Peyton Manning to about $15-16 million a year, 2-3 years. That's probably about what Peyton can expect at the most, given his neck.
(2) Sign Mike Wallace. Yes they lose their 1st round pick. Or just sign VJax, either way.
(3) Re-sign Goldson.
Then they keep their top-ranked defense, and their offense looks like this:
QB - Manning
RB - Gore
WR - Wallace/VJax, Ginn, Crabtree
TE - Davis
I mean, holy crap, that team suddenly is unbelievably scary.