Some help with a piece

[wair]

Hello, I've been playing piano for about a month. I'm currently learning a piece called Futatsu No Kodou To Akai Tsumi. here is a youtube link to the song

. I am also an advanced guitarist. Any way my question is I can play the beginning of the piece perfectly up until the scale run. but then when it becomes more intricate with both hands I'm having alot of difficulty. Do you think this song is too hard for me to learn at my current level ? Also I have a 61 key keyboard this piece requires an 88 key piano, if my level permits me to continue this piece would there be any way around this issue ? I plan to purchase an 88 key piano but not yet maybe if I can play this piece successfully I will.

Your help is much appreciated.