The wrong size screen is the wrong size.....period. Unless your screen, even at 135" diagonal, has the appropriate amount of gain, your resulting image will be nothing like it should / could be.
At a 23' foot throw, and even with 1.3 gain, the best the Z5 can muster is 9 ft Lamberts. Drop 10' of that throw and you'd have 13 ft Lambeex calibrates rts, a figure that would be more in keeping with providing a vibrant image.
But at 23' @ 150" diagonal w/1.3 gain you'd get only 7 ft Lamberts and at 1.0 gain just 6 Ft Lamberts.
That is no figure to settle for by any stretch, and the mix-up with your shipped screen excalibrates what is already a very poor match-up choice.
Myself, I'm a stanch proponent of "BIG"...and not just "Big" but BIG
But you HAVE to do "BIG" right, or you wind up with nothing but a big disappointment. I respect anyone's desire to get "The BIG Picture". I also acknowledge that for many such, seeing BIG the first time, and without a standard for measure to judge against, BIG can look pretty darn spectacular even when it's dimmer by 1/2 than it really should be.
But in your case, at about 500- to 700 Hrs on the Z5's bulb, you'll be watching an image that is dimmer that it is now on Low Lamp. Not something you want to deal with.
Monoprice is no slouch about correcting a mix-up. Don't wonder "IF" they will issue a Return Tag and re-ship a smaller screen.............EXPECT IT!
They made a BIG mistake, and it will have a very negative impact on your viewing pleasure. But they are after all a Company that sells screens "you" order, and after checking your past Posting back to 01-01-08, I don't see where you inquired or considered the size selection of your screen as relates to your PJ's output potential.
That Sir, is almost criminal on a Forum where the is so much good advice available from so many with bona fide experience. Not the first time it's happened though, I must say.
But Monoprice has given you a reprieve! They messed up! Especially if you have an invoice that states you were to receive a 135"er instead of 150" So use the opportunity to do it right. Have 'em recall that thing, and re-order a smaller screen. If you think it's possible, relocate your PJ as close as possible. Even at 135" diagonal, the Z5 can be as close as 18' (...and still be only midway through it's 2.0 Zoom ratio....) and then it will deliver at least 8 ft. Lamberts @ 1.0 gain ...... and 10 ft. Lamberts @ 1.3 gain. (all on "Normal lamp") That is still not "stellar" but significantly brighter than 6 ft. Lamberts @ 150" diagonal (122" would be "Mo Bedder" still. )
I can't know why your shooting from the next County....you've posted nothing to that effect. Size as viewed from a distance becomes the same to look at as a smaller screen viewed from closer in. The Z5 has enough resolution, and a smooth enough image that you can crowd in as close as a 1.2 ratio of Screen/Seating Location.
Some of the above may seem slightly critical, but it's all well meant, and believe this; few others will advocate "SIZE" as I do (...and have done...) But it has to be done right or it's not really worth doing IMHO.