Given that the club is losing Luai & I think we lack that edge in leadership, but have several talented players on the roster- I think Josh Papali'i & Tyson Frizell are the right types to add to the squad.
Add them to May, Twal, Seyfarth, Pole, Sione Fainu, Bunty...and as a bridge to Duncombe & Topou-Moors etc- it just means we don't have that drop off like we do now.
What we have seen of Heyward & Lanyon suggest they could back up Api.
Then add Blore to the mix.
Other than Blore, I don't think they break the finances too badly. Add depth & experience & don't block the path of juniors.
In the backs, I'd still look at bring Talau back for one of the bottom Top 30 spots.
If Papali'i can give us 20 minutes a game to rest May, if Frizell can give Twal a rest or cover wider if needed, for 20 minutes- you can rotate Sione & Pole over & over to keep their impact fresh. Blore would be a luxury. Maybe Roberts plays that role instead from within.