Great site for sure.
It is not really additions but some details.
My copie of "Just Dennis" on Observer label (Ja) has a Trojan laminated cover with a "made In Jamaica" sticker on back cov. The mat is the same as the Trojan one (TRLS 107) with addition of "FRM" after the matrix. Mat is hand written whereas the UK press has "mechanical written" matrix.
I have a Ja copy of "Deep Down" with a totaly different label compared to yours. Mine has a white/yellow checked label and a black printing (with the classic Obs label design). Matrix are "GUSSIE 1010 A/B". The back cover has also differences. Actually it don't have the writting on bottom. After the "Recorded at", "Engineer",..., "Distributed By: Observer Records, Kingston" infos, there is only one sentence: "Distributed In jamaica By" and nothing else. Last info it has: "Lithographed in Jamaica by Stephenson". My copy was certainly an exported one cause there is no stamp for local distribution but there are "VP records & the NY adress" stamped on label. Yours seems to be a US/Canadian one. Didn't know there was to different press.
last, the "So Long Rastafari" LP on Harry J is a reissue of the "Deep Down" LP. You should perhaps add this info? I assume you knew that detyail.
Regarding the 12" & 7", there is a 12" I didn't find: "Why Fool" (Thompson Sds). This one is a DEB prod, but it appears on Thompson Sds in Ja. Don't know on which label appeared the 7".
There is also a prerelease of the "Promised Land" 12" with only title and artist stamped on the label.
PS if you want pics of some labels, just send me a personnal message. i'll try my best.