Stringer resoration on a 20 sf

[71kidcasper]

I have a 71/72 20 sf that I am starting to restore. I have been contemplating my options when it comes to repairing the stringers. I have seen several different ways to repair them on this site. My boat has the four stringers which are about four inches wide. I have an idea that I would love some input on. I have been thinking about filling up the space between the stringers on the port and starboard sides with 4lb. expanding polyurethane foam and then glassing the new larger stringer. Has anyone else already tried this? Basically I want it to look like the stringers in the later built boats 74 and later.