The LH351D 3500k 90 cri can be ordered from Digikey. https://www.digikey.com/product-detail/en/samsung-semiconductor-inc/SPHWHTL3DA0GF4UPP6/1510-2331-1-ND/
Shipping is usually around 5 or 6 bucks usps.
Contactcr tested it here. LH351D 90CRI Spectrum Tests - #32 by contactcr
The bin I linked is the best, they offer another bin but its not as good as the UPP6.
Finding the right size TIR will be challenging but most of the time the size is listed in the descriptions. Pull your reflector out and measure diameter at the top and the height.
I would try aliexpress and search for “”led optic”“:https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20200521110728&SearchText=led+optic for xpl, xpg, LH351D 3535 sized optic.
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I thought of one more thing, you could use the OL stipple method on your reflector to smooth out the beam a little more.
Details here. Video - How I Stipple a Reflector
Comparison photos here. Beam Shots - SMO Reflector versus Stippled Reflector - Just so you can see the difference.
You will lose about 7 to 10 % in the lumens in the testing I have done but it makes a big improvement and your going to lose some lumens either way you go anyway.
There’s also DC-fix. DC-Fix Diffusion Film Sale
None will be as floody as a wide angled TIR but pretty good improvements can be made with the other methods.