......I would try a 300 cut at 30” with 250 point.......
I bet that would a good guess Felix.
So I have quite a few heavy arrow setups and 100lb+ gold tips do come into the picture with at least a 29" draw at 60lbs or more with weight forward arrows. I'm probably shooting 65lbs or more, on my 60lb marked bows. I have 100lb+ in full length, 31 1/4 and some that someone else cut down to 30 which is too much in my opinion. My 61@27 Pronghorn shooting at 29 inches like the full length 100lb+s. My 60@28 64inch PL likes the cut down to 31 1/4 100lb+. These arrows have 100 grain brass inserts and around 250 grains for the point, which you should be able to find a broadhead for ....
But, all that said you should be able to reduce the weight on your 300s up front until you at least find something that works even if your not going to shoot that. Then you know where your at so to speak.
Like MCDave said in a similar post cut down arrows really get difficult to bend it seems. I like to just go up a size instead and do the fine tuning with point weight if possible.
I have a number of bows that like a full length 300 Beman ICS hunters. 100 grain insert and usually 200 grain point. So My 48lb PLX likes those. My Morrison Max IIs (border) at 50lbs also shoot that arrow well as do many of my hypo bows that are around 50lbs ... for reference ......
So as you might guess I have those two lengths in every arrow size although 35/55 are already shorter stock. Then I can shoot a bow I haven't got out for a spell and get in the game pretty quick by just choosing a size to start at. it works .....