Ahh.... ok monkeyeyes... I thought you had created the drawing yourself, sorry !
Try the 40% option - but here's a little tip. Print out what you can of the drawing at 1:1250 and measure between a few points, using a 1:1250 scale ruler if you have one and make a note of the distance. Print out at the 40% as suggested above and re-measure between the same points using a 1:500 scale ruler. If they are (approximately) the same distance, then you know you've got the % correct.
Failing that, email me a copy of the drawing (
[email protected]) and I'll transfer it to the correct scale for you and email it back to you in the next day or so - just change the phrase myusername to my actual user name lol)