If you are performing the bosses you will require a whole lot better armor. If you go in with just full rune, it will not take you long to OSRS gold have slaughtered. You'll need barrows/god armor (The kind you get from the dungeon, like Bandos) a LOT of food, at LEAST 80+ ALL battle stats and 70+ Prayer will make your life a great deal simpler.
In short: Get more moneyup and down your combat stats first. I'd advise that you get each combat level up one level , then try and receive Prayer to 60, bare minimal. Consider doing it through slayer for some good cash, which you actually need. Rune is nice. Barrows is better but rune is great if you do not have the money to spend. You can even array him. If you go with a group of 4/5 you can last maybe 10 kills rune. Likely 15 using Barrows, it doesn't actually make that much of a difference.
Rune is economical and easy to replace, since there's a constant supply of it. You don't need Barrows. He will not require a lot of meals either. A full devise of Tuna potatoes would be good. I went with like 75 all battle stats. It took me a while to find a group, and ironically I was the second greatest level in that team, and we managed to get around 10 kills in. Entirely off subject to the query, but stop banging on about Slayer. He's 42 Slayer. What is he going to kill to make'decent money' there? Terror Dogs for Granite Helms? But if you're so adamant that Rune is a heap of shizzle then what is he going to Buy RS gold manage that?