Lag bolts vs wood screws for reinforcing garage door header
Jacob,  here is my suggestion.  I would use a 2x4 or 2x6" block at least 24" long.  Then I would use some 3" construction screws.  Make sure you pre-drill the block first.  The screws should slip through the block easily.  Then use washers.  The construction screws look a lot like sheet-rock screws but are a lot stronger.  They will have a Torx drive head.  Use at lease 5-screws.