Trinidad & Tobago Overprints - Sg Help Requested

I am a nut for modern surcharges that are produced for actual postal use instead of issues produced to extract money from collectors.

I am hoping there is someone out there with access to a Stanley Gibbons catalog that can help me with some info (and I'm not sure if this would be the general Part 1 catalog or some specialized West Indies catalog).

For the 75c on 40c bird, I know there is a SG number of 883, but I have been led to belive this exists on both the watermark 14 (block letters) and watermark 16 (script letters), and I don't know which version 883 refers to nor what the other number would be. Mine is the block wmk version, so I assume it is the more common one.

For the $1.00 on $2.25 bird, I have seen on Tony Bray's web site (new issue dealer in the UK) where he lists:
$1.00 on $2.25 2013 L0.95 out of stock 2014 L0.25
but it is my understanding the $1.00 on $2.25 was released in 2012. The images he shows are low resolution, so it is hard to be sure, but the one he labels 2013 appears to possibly have a narrower font while the 2014 a bolder font. Scott lists a $100 error of design version, and two different $1.00 versions, but the font of the $ and the 1 are very obviously different, while on Bray's site they look similar, so I am clueless here.

For the $1.00 on $2.50 bird with no obliterator block, I have seen (on Tony Bray's web site??) a listing for a 1203 and 1204, but the images look identical to me. Is it a watermark difference?