Cyprus Overprints On Early GB Stamps

Hi. Sorting through my Cyprus collection and came across a couple of nice ones (picture 1 and 2). SC/SG #1 is unused, overprint looks correct and the plate number is 12 (sorry can't really see it in the picture), making me believe that this stamps is genuine . Another one is SC#8 SG/7, unused, overprint looks correct and the plate number is 220, also making me believe that this stamp is legit .

However, the other two (pictures 3 and 4) are not making much sense to me. Overprint does not look the ones in the catalogue, plate number is 13 on 1/2p stamp and 90 on 1p stamp. Also, numeral cancel on 1p stamp looks like 673 to me, is that even in Cyprus? However, overprints on these two stamps looks very similar, which confuses me. Unless these are the work of the same artist, then there have to be some other explanation for these two stamps.

That third stamp appears to very much have a forged overprint. The fourth, at least, appears to be of a better quality but of the wrong typeface. The cancel, I think 613, is for Petersfield (Hants). 673 would be for Mevagissey in Cornwall.

The plate 220 Penny Red looks genuine.

I am not 100% convinced by the halfpenny overprint. Also, I am wondering if the stamp had a cancellation removed.

The Cyprus numerals were 942, 969, 974, 975, 981, 982, 098, D47, D48

NSK.

Thank you so much for all that wonderful input. I really appreciate your time and help. The first stamp does looked a bit washed out. However, what I think you are suspecting as removed cancelation is the watermark showing through. I've compared that overprint with some pictures on the web from sold auctions (not ebay :) of course) and it does look very similar to the examples I found. Of course, I cannot be 100% sure without the cert.

I allowed for the watermark. This will not cover the whole stamp. It vaguely appears like there was a barred cancel, but the paper of these stamps does show some strange effects in pictures. Another thing that attracts the eye is the diagonal line to the right of the southwest 'H.'

When I say "not 100% convinced," it, really, is not more than an inkling of doubt. It looks genuine but there are a few things that attract attention.