How to quickly analyze a property quickly

Hello!,
How to analyze a property quickly

SampleUseCase:
House sells for $300,000 fixed up. Repair budget is around $60,000.$300,000 x 0.75 = $225,000
0.75 factor to account for profit, closing costs on both ends, agent fees when I sell, and the months I hold the property while it is being worked on. Should I use different factors for different year built houses? Any online free tool I can use for this analysis before sending a contractor (by paying 500$) to get rehab estimates if numbers seem okay?
$225,000 - $60,000 = $165,000I can offer 165k?But one house was built in 1910 and another house was built in 2010 ( everything else is the same, for example both houses sell at 300k and both houses need 60k rehab budget). How to account for that? How much can I offer for a 1910 property?How much can I offer for a 2010 property?Thanks