BRRRR calculation assistance

[Kayte Flyte]

Hello, I am new to investing and want to make sure I'm thinking about BRRRR investing correctly. Please let me know if I'm thinking about this inaccurately in this hypothetical situation. Let's say I'm looking at a property for $350,000 purchase price, will put 25% down ($87,500) and it needs $50,000 in renovation costs. The ARV is estimated to be $450,000. If I'm following the 70% rule then I should not spend over $265,000. So let's say I invest a total of $315,000 with purchase price and renovations. When I refinance for 80% cash equity , if the appraisal comes back to be $450,000 that equates to 450,000-315,000 = 135,000 x 0.8 = $108,000 in cash equity right? That obviously does not include any costs that accrued from taxes, financing charges, etc, but otherwise that's $108,000 I can use to move forward with my next property?

Thank you in advance for your time and assistance!