10Gb on OM1 over distance... Want to add an OM3 transition, will this screw me?

I have a 6-strand run of OM1 (yes, 62.5/125) that's approximately 220ft long, between two closets in a building that is very difficult to wire. Replacing this cable is not likely to happen any time soon (especially since there's been talk of moving).

I'm currently running 2x10Gb over 2 pairs in this cable without a problem. It's been up for months and there are zero error counters on either side of either link. Power level as shown on a Cat3850 at one end (the other side is an HP 5406zl):

 Optical Optical Temperature Voltage Current Tx Power Rx Power Port (Celsius) (Volts) (mA) (dBm) (dBm) --------- ----------- ------- -------- -------- -------- Te1/0/20 27.4 3.31 6.6 -2.2 -4.2 Optical Optical Temperature Voltage Current Tx Power Rx Power Port (Celsius) (Volts) (mA) (dBm) (dBm) --------- ----------- ------- -------- -------- -------- Te2/0/20 27.8 3.31 8.3 -1.8 -2.6 

I want to move these connections (they're in a port channel) off of the Cat3850 stack they are on and over to a pair of Nexus 93180-YC-EX, along with some other things that are landing on the 3850s (trying to get the 3850 stack out of the equation so it can be used elsewhere, long story).

The other stuff landing on the 3850s are all OM3 and within spec, I have 12 other strands (6 pairs) involved. I'm planning on throwing a 24-strand MTP cable and cassettes on both ends of it, because these two racks are around 20-25 feet apart and I don't want to run a bunch of stuff through the drop ceiling between them if I can just run one MTP cable (24 strands so I have some extra headroom for growth if needed).

The real question here - would plugging OM1 into OM3 at a cassette, and then through the (relatively short) OM3 MTP, and back out a cassette and an OM3 patch cord at the other end, be likely to cause this (already over-spec but seemingly OK) link to fail?

Or does it all come down to straight power budget, and as long as I don't lose too many dB to the conversion, it should keep ticking? I can't imagine that the OM1->OM3 plus the connectors are going to lose 4-5 dB, but I've also never tried it before...

My coworker feels that it's "safer" to just keep the whole run OM1, order a pair of longer patch cables and run them next to the MTP, and hope that an extra 20-some feet of patch cord isn't enough to kill it. I agree with him, but I'd rather not run more cables if I don't have to. Just not sure (a) how much loss to expect from the 62.5->50 transition, and (b) whether "functional 10Gb link" is simply a matter of light levels or if something else could come into play here.