300m of OM1 will NOT work with 10GBASE-SR, as JFL and kaya atabey have already pointed out. From 2003, it's quite likely OM2 which won't work with 10G-SR either at that distance. Additionally, patch cables should always match the plenum cable, OM1 won't help here either.
You need to make sure what kind of cable you've got. If it is less than OM3 you'll need to redeploy(!) - also consider switching over to SMF - or find a 10GBASE-LX4 transceiver pair. -LX4 is designed for legacy MMF and will just do 300m even over FDDI grade - it might be expensive and hard/impossible to get though. HPE doesn't sell -LX4 any more. There's also 10GBASE-LRM but that maxes out at 200m.
Another, cheaper option would be to test single-strand 1000BASE-BX10 transceivers (J9142B/J9143B for HPE switches). While these are designed for SMF, they should work on MMF as well, on OM1 for possibly as far as 500m (very much like -LX). If they work you could then aggregate the two or possibly more MMF strands. -BX SFPs from HPE are very expensive as well but there are many 3rd party vendors around.
Note that any single flow would still be limited to 1 Gbit/s, but multiple concurrent flows would become possible. Also note that -BX operation over MMF is not within any standard - don't expect support and observe your company policies on that.