Just finished a farm with a similar budget. Where are you sourcing cards from? That is going to be one of your biggest issues if you want to be cost effective. Would be happy to send you pics and answer any questions if you shoot a PM but I would start by doing a few things -
1. Secure a relationship with a card distributor and get a line of credit established with them
2. Figure out room dimensions and what kind of cooling considerations will have to be taken into account
3. Figure out power. Does the space have 3 phase available to it? How many amps?
4. Figure out who will be managing it. Your friend doesn't want to hodl - does that mean he doesn't follow crypto? Profitability is going to be drastically reduced in this market unless mining is done intelligently.
5. Who is going to build the farm? There are a lot of things that come along with the construction of a $50K build that aren't issues when you're building one or two rigs in your garage.
Depending on the amount of space available, you may want to go for more cheaper cards, or less more powerful cards. Personally, I prefer having as high of hash density as possible so that I can use fewer 6-8 card rigs total. 1080 TI are great for this, but there are many opinions on this.
Hope this helps!!