WIP Cream jacket

Here is one of my wips (works in progress).  It is a cream silk opera jacket the pattern is in the current "Crochet" magazine. If you want to see the image from the magazine go here but it won't be the pattern just the image.
I got this silk yarn thrifting 4 balls of it for a total of 3 dollars for all of them not each.   Not a bad price at all for 100% silk yarn that is super soft to the touch.  (Update: I decided to look on line and found the exact same yarn for 160.00 that would include shipping a very good find indeed)
The pattern called for 500 grams of the requested cotton yarn.  I didn't want to go buy anything for this and I only had only 450 grams of this well I guessed it would work and I could just shorten the sleeves if need be.  I guess I will not have to worry about that though. So far I have used 1 ball and about 10 yards of the next and I am already half way done.  So I am guessing that cotton yarn is way heavier than silk.  Meaning per gram I have more yardage than the  cotton did.  Sso I will have more yardage and less weight a nice spring jacket which is just what I wanted.  Also I will still have the left over silk yarn to play with.
In the pattern this is the point where I am supposed to add the lace edge but I want mine to be more closed in the front and longer in the back so I am going to modify the pattern.  As long as the outer edge is divisible by 18 ( which is what the lace edging uses) I can make it longer and that is an easy thing to do.
I am thinking if I have enough yarn left over I might try making one similar to this but knitted since knitting lake less yarn than crochet I am thinking it may just work.  The pattern only comes in crochet but how hard can it be really to make it knitted.  I already know how the crochet one was constructed so it should be easy peasy watch I will be wrong ;o).