Here's my take on the recipe conversion. Two points: Gladfield's Sour Grapes Malt is just acidulated malt. It's not 736 SRM, this is a mistake. It's about 3.5 ebc. Don't omit this. It's important to the overall flavour of the beer. Normally it would be used for correcting the pH of the mash, but there's no need to because of the 4 dark malts. It is, however, necessary for the flavour- I always use it in my Guinness clones. Second point is that the NZ brewers have adapted the recipe to their own ingredients, matching them as closely as possibe, and it's not always clear what they've substituted from, fore example, I can't find a crystal malt of 96.4 srm (190 ebc) so it's a toss up between a crystal around 155 ebc or one around 220 ebc. I've converts srm to ebc below.
Recipe for 20 litres, abv 6.0% : 36 ibus : OG 1063 ; FG 1018 (that seems a bit high to me!)
3Kg Crisps Best Ale Malt 5.5 ebc
1.3 Kg Flaked Barley
700 g Munich Malt around 15 ebc. (I would be using Crisp's which is a tad higher)
336 g Crystal Malt 190 ebc (I'd choose Crisp's 155 ebc rather than the dark at 220 ebc but suit yourself. I might change my mind when I do it)
224 g Roast Barley 1450 ebc (Mine's 1300 ebc)
112g Acidulated Malt 3.5 ebc. (Most of these are German, Wyermann is typical)
NB. Crisp's crystal malt descriptions are a nightmare: they call "light" what everyone else calls "medium" and "medium" what everyone else calls "dark". Go by the ebc.
Hops:
52g Fuggles pellets @ 4.5% alpha acid for 90 minutes to give 26 ibus
32g EKG pellets @ 5.5% alpha acid for 30 minutes to give 10 ibus
Irish moss or Protofloc last 10 minutes.
Irish Ale yeast.
Check for glaring errors as I've got a thick head this morning due to curry poisoning even though I tried to wash it all through with beer.