Marshall Islands Forgery ?

I have posted several stamps on this forum for discussion, these stamps came from a bulk lot I bought by auction many years ago all from a little envelope marked forgies to date the forum has provided my with expert knowledge to confirm this is the case with those stamps posted. This stamp is the last of the stamps from this envelope - the overprint straight away seems dubious - not that I collect this country, I m sure I will get some good info from the forum.
Sydneyboy

The 3d. overprint was only applied to the 25 and 30 Pf values. The proper overprint for the 80 Pf would be the 8d.

You can read more about the G.R.I. overprints here:

http://marshall.csu.edu.au/Marshall...p_Nauru.html