Noob: Cracking SHA1 with known partial

Hi Guys, 

First time posting on this kind of forum, so go easy on me please. 

I want to see how fast I can brute force a SHA1 hash based on an input of between 53 and 55 characters. 

Essentially I want to retrieve a shared key value which is inserted into a hash function surrounded by non-secret content

e.g. PublicInfo|foo|sharedkey|bar|1234

I know the first 8 characters, and I know the final 37 of the SHA1 input. 
I also know that the missing 8-10 characters are alphanumeric only (no special characters) 

Can i get hashcat to spit out the correct 8-10 characters to produce the hash I have? 

What is involved in getting this setup to run?