You don't mention where Dick Snell got this song, but it appears to be the set noted by the Hammond brothers from Joseph Elliott at Todber, Dorset, in September 1905. It was printed in The Journal of the Folk-Song Society vol 7 (issue 27) 1923, pp.61-62.

A few words vary in minor particulars and spelling, with the usual interjections of "well" and the like. The final line of verse 2 I can't help much with, as Mr Elliott sang "And if you fire a shot at all you'll walk the plank"; Henry Hammond indicated that there were words missing. Presumably the line has been re-constructed here. The word you want will be "yardarm" no doubt.

Mr Elliott sang the parts you mark as doubtful as follows:

They struck down our blue silk ensign, thinking a warlike ship to take
But we gave them such a peal, my boys, that made their hearts to ache.

And they did loud for mercy cry, but to none of them 'twas due.

The bold pirate he bored from us and he tried for to run away
But a broadside from our warlike ship did causèd him to stay
We hpisted out our boats, my boys, and boarded him immediately
And there we found the bold pirate with his two legs from his thigh.

"Forward" in the penultimate verse is right.